Significant Accounting Policies (Narrative) (Details) - USD ($)
|
3 Months Ended |
12 Months Ended |
|
|
|
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
Jan. 03, 2018 |
Jan. 05, 2017 |
Dec. 31, 2014 |
| Significant Accounting Policies [Line Items] |
|
|
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|
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| Capitalized development and construction salaries and other related costs |
|
|
$ 2,200,000
|
$ 2,600,000
|
$ 4,200,000
|
|
|
|
| Construction, tenant improvement, and development in-progress |
$ 559,500,000
|
$ 361,100,000
|
$ 559,500,000
|
361,100,000
|
|
|
|
|
| Maximum period after cessation of major construction activity that projects are considered complete |
|
|
1 year
|
|
|
|
|
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| Threshold of investment value for discontinuation of equity method accounting |
0
|
|
$ 0
|
|
|
|
|
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| Amortization of deferred financing costs |
|
|
4,612,000
|
4,582,000
|
3,790,000
|
|
|
|
| Loss from extinguishment of debt, net |
|
|
(421,000)
|
12,420,000
|
|
|
|
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| Write off of unamortized deferred financing costs |
|
|
400,000
|
700,000
|
0
|
|
|
|
| Deferred leasing costs |
|
|
3,146,000
|
3,270,000
|
3,521,000
|
|
|
|
| Difference between the estimated net basis and net assets of the rental property for federal income tax purposes |
231,067,000
|
|
231,067,000
|
|
|
|
|
|
| Taxable income |
|
|
97,037,000
|
$ 30,208,000
|
$ 63,285,000
|
|
|
|
| Deferred tax asset |
$ 11,700,000
|
|
11,700,000
|
|
|
|
|
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| Income taxes, material adjustment amount |
|
|
$ 0
|
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|
|
|
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| Common stock, shares outstanding |
89,914,113
|
89,696,713
|
89,914,113
|
89,696,713
|
|
|
89,696,824
|
|
| Common units outstanding |
10,438,855
|
10,488,105
|
10,438,855
|
10,488,105
|
10,516,844
|
|
10,488,105
|
11,083,876
|
| LTIP units outstanding |
1,230,877
|
657,373
|
1,230,877
|
657,373
|
|
|
657,373
|
|
| Distributions payable, record date |
Jan. 03, 2018
|
Jan. 05, 2017
|
|
|
|
|
|
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| Distributions payable, approved date |
Dec. 12, 2017
|
Dec. 13, 2016
|
|
|
|
|
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| Common stock dividends and common unit distributions per share |
$ 0.20
|
$ 0.15
|
|
|
|
|
|
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| Dividends paid per common share |
|
|
$ 0.70
|
$ 0.60
|
$ 0.60
|
|
|
|
| Dividends paid, percent representing ordinary income |
|
|
|
|
90.00%
|
|
|
|
| Dividends paid, percent representing return of capital to shareholders |
|
|
|
100.00%
|
10.00%
|
|
|
|
| Dividends paid, percent representing capital gain |
|
|
100.00%
|
|
|
|
|
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| Restricted stock expense |
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|
$ 7,447,000
|
$ 5,646,000
|
$ 2,219,000
|
|
|
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| Distributions payable, pay date |
Jan. 12, 2018
|
Jan. 13, 2017
|
|
|
|
|
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| Increase (decrease) to deferred tax assets |
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|
(5,300,000)
|
|
|
|
|
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| Increase (decrease) to valuation allowance |
|
|
$ (5,300,000)
|
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|
|
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| Subsequent Event [Member] |
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| Significant Accounting Policies [Line Items] |
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| Common stock, shares outstanding |
|
|
|
|
|
89,914,658
|
|
|
| Common units outstanding |
|
|
|
|
|
10,438,855
|
|
|
| LTIP units outstanding |
|
|
|
|
|
1,230,877
|
|
|