Segment Reporting
 3 Months Ended 12 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Segment Reporting [Abstract]    
Segment Reporting
Segment Reporting
Management reviews the performance of individual properties and aggregates individual properties based on operating criteria into two reportable segments—commercial real estate investments in data centers and healthcare, and makes operating decisions based on these two reportable segments. The Company’s commercial real estate investments in data centers and healthcare are based on certain underwriting assumptions and operating criteria, which are different for data centers and healthcare.
The Company evaluates performance based on net operating income of the individual properties in each segment. Net operating income, a non-GAAP financial measure, is defined as rental revenue, less rental expenses, which excludes depreciation and amortization, general and administrative expenses, asset management fees and interest and other expense, net. The Company believes that segment net operating income serves as a useful supplement to net income because it allows investors and management to measure unlevered property-level operating results and to compare operating results to the operating results of other real estate companies between periods on a consistent basis. Segment net operating income should not be considered as an alternative to net income determined in accordance with GAAP as an indicator of financial performance, and accordingly, the Company believes that in order to facilitate a clear understanding of the consolidated historical operating results, segment net operating income should be examined in conjunction with net income as presented in the accompanying condensed consolidated financial statements and data included elsewhere in this Quarterly Report on Form 10-Q.
Non-segment assets primarily consist of corporate assets, including cash and cash equivalents, real estate and escrow deposits, deferred financing costs attributable to the revolving line of credit portion of the Company's secured credit facility and other assets not attributable to individual properties.
Summary information for the reportable segments during the three months ended March 31, 2019 and 2018, is as follows (amounts in thousands):
 
Data Centers
 
Healthcare
 
Three Months Ended
March 31, 2019
Revenue:
 
 
 
 
 
Rental revenue
$
26,677

 
$
19,790

 
$
46,467

Expenses:
 
 
 
 
 
Rental expenses
(6,965
)
 
(2,163
)
 
(9,128
)
Segment net operating income
$
19,712

 
$
17,627

 
37,339

 
 
 
 
 
 
Expenses:
 
 
 
 
 
General and administrative expenses
 
 
 
 
(1,403
)
Asset management fees
 
 
 
 
(3,494
)
Depreciation and amortization
 
 
 
 
(18,246
)
Income from operations
 
 
 
 
14,196

Interest and other expense, net
 
 
 
 
(9,835
)
Net income attributable to common stockholders
 
 
 
 
$
4,361

 
Data Centers
 
Healthcare
 
Three Months Ended
March 31, 2018
Revenue:
 
 
 
 
 
Rental revenue
$
23,721

 
$
17,573

 
$
41,294

Expenses:
 
 
 
 
 
Rental expenses
(5,937
)
 
(2,353
)
 
(8,290
)
Segment net operating income
$
17,784

 
$
15,220

 
33,004


 
 
 
 
 
Expenses:
 
 
 
 
 
General and administrative expenses
 
 
 
 
(943
)
Asset management fees
 
 
 
 
(3,099
)
Depreciation and amortization
 
 
 
 
(13,717
)
Income from operations
 
 
 
 
15,245

Interest and other expense, net
 
 
 
 
(7,741
)
Net income attributable to common stockholders
 
 
 
 
$
7,504


There were no intersegment sales or transfers during the three months ended March 31, 2019 and 2018.
Assets by each reportable segment as of March 31, 2019 and December 31, 2018 are as follows (amounts in thousands):
 
March 31, 2019
 
December 31, 2018
Assets by segment:
 
 
 
Data centers
$
1,008,793

 
$
1,001,357

Healthcare
893,057

 
900,114

All other
59,179

 
62,358

Total assets
$
1,961,029

 
$
1,963,829


Capital additions and acquisitions by reportable segments for the three months ended March 31, 2019 and 2018 are as follows (amounts in thousands):
 
Three Months Ended
March 31,
 
2019
 
2018
Capital additions and acquisitions by segment:
 
 
 
Data centers
$
995

 
$
52,213

Healthcare
78

 
5,629

Total capital additions and acquisitions
$
1,073

 
$
57,842
Segment Reporting
Management reviews the performance of individual properties and aggregates individual properties based on operating criteria into two reportable segments—commercial real estate investments in data centers and healthcare, and makes operating decisions based on these two reportable segments. The Company’s commercial real estate investments in data centers and healthcare are based on certain underwriting assumptions and operating criteria, which are different for data centers and healthcare.
The Company evaluates performance based on net operating income of the individual properties in each segment. Net operating income, a non-GAAP financial measure, is defined as total revenues, less rental and parking expenses, which excludes depreciation and amortization, general and administrative expenses, acquisition related expenses, asset management fees and interest and other expense, net. The Company believes that segment net operating income serves as a useful supplement to net income (loss) because it allows investors and management to measure unlevered property-level operating results and to compare operating results to the operating results of other real estate companies between periods on a consistent basis. Segment net operating income should not be considered as an alternative to net income (loss) determined in accordance with GAAP as an indicator of financial performance, and accordingly, the Company believes that in order to facilitate a clear understanding of the consolidated historical operating results, segment net operating income should be examined in conjunction with net income (loss) as presented in the accompanying consolidated financial statements and data included elsewhere in this Annual Report on Form 10-K.
Non-segment assets primarily consist of corporate assets, including cash and cash equivalents, real estate and escrow deposits, deferred financing costs attributable to the revolving line of credit portion of the Company's secured credit facility and other assets not attributable to individual properties.
Summary information for the reportable segments during the years ended December 31, 2018, 2017 and 2016, is as follows (amounts in thousands):
 
Data Centers
 
Healthcare
 
For the Year Ended
December 31, 2018
Revenue:
 
 
 
 
 
Rental, parking and tenant reimbursement revenue
$
103,226

 
$
74,106

 
$
177,332

Expenses:
 
 
 
 
 
Rental and parking expenses
(27,289
)
 
(10,038
)
 
(37,327
)
Segment net operating income
$
75,937

 
$
64,068

 
140,005

 
 
 
 
 
 
Expenses:
 
 
 
 
 
General and administrative expenses
 
 
 
 
(5,396
)
Asset management fees
 
 
 
 
(13,114
)
Depreciation and amortization
 
 
 
 
(58,258
)
Income from operations
 
 
 
 
63,237

Interest and other expense, net
 
 
 
 
(34,364
)
Net income attributable to common stockholders
 
 
 
 
$
28,873

 
Data Centers
 
Healthcare
 
For the Year Ended
December 31, 2017
Revenue:
 
 
 
 
 
Rental, parking and tenant reimbursement revenue
$
62,377

 
$
62,718

 
$
125,095

Expenses:
 
 
 
 
 
Rental and parking expenses
(17,571
)
 
(8,525
)
 
(26,096
)
Segment net operating income
$
44,806

 
$
54,193

 
98,999


 
 
 
 
 
Expenses:
 
 
 
 
 
General and administrative expenses
 
 
 
 
(4,069
)
Asset management fees
 
 
 
 
(9,963
)
Depreciation and amortization
 
 
 
 
(41,133
)
Income from operations
 
 
 
 
43,834

Interest and other expense, net
 
 
 
 
(22,555
)
Net income attributable to common stockholders
 
 
 
 
$
21,279

 
Data Centers
 
Healthcare
 
For the Year Ended
December 31, 2016
Revenue:
 
 
 
 
 
Rental, parking and tenant reimbursement revenue
$
12,929

 
$
43,502

 
$
56,431

Expenses:
 
 
 
 
 
Rental and parking expenses
(2,509
)
 
(5,655
)
 
(8,164
)
Segment net operating income
$
10,420

 
$
37,847

 
48,267

 
 
 
 
 
 
Expenses:
 
 
 
 
 
General and administrative expenses
 
 
 
 
(3,105
)
Acquisition related expenses
 
 
 
 
(5,339
)
Asset management fees
 
 
 
 
(4,925
)
Depreciation and amortization
 
 
 
 
(19,211
)
Income from operations
 
 
 
 
15,687

Interest and other expense, net
 
 
 
 
(4,390
)
Net income attributable to common stockholders
 
 
 
 
$
11,297


There were no intersegment sales or transfers during the years ended December 31, 2018, 2017 and 2016.
Assets by each reportable segment as of December 31, 2018 and December 31, 2017 are as follows (amounts in thousands):
 
December 31, 2018
 
December 31, 2017
Assets by segment:
 
 
 
Data centers
$
1,001,357

 
$
909,477

Healthcare
900,114

 
813,742

All other
62,358

 
54,725

Total assets
$
1,963,829

 
$
1,777,944


Capital additions and acquisitions by reportable segments for the years ended December 31, 2018, 2017 and 2016 are as follows (amounts in thousands):
 
For the Year Ended
December 31,
 
2018
 
2017
 
2016
Capital additions and acquisitions by segment:
 
 
 
 
 
Data centers
$
114,944

 
$
472,438

 
$
314,030

Healthcare
117,971

 
164,445

 
229,670

Total capital additions and acquisitions
$
232,915

 
$
636,883

 
$
543,700