Future Minimum Rent (Tables)
3 Months Ended 12 Months Ended
Mar. 31, 2019
Dec. 31, 2018
Leases [Abstract]    
Schedule of Future Minimum Rental Income from Non-Cancelable Operating Leases  
The future minimum rent to be received from the Company’s investment in real estate properties under non-cancelable operating leases, including optional renewal periods for which exercise is reasonably assured, as of December 31, 2018, for each of the next five years ending December 31 and thereafter, are as follows (amounts in thousands):
Year
 
Amount
2019
 
$
145,109

2020
 
146,826

2021
 
149,142

2022
 
144,560

2023
 
141,915

Thereafter
 
1,005,017

 
 
$
1,732,569

Schedule of Future Minimum Rental Payments Under Non-Cancelable Ground Leases
The following represents approximate future minimum rent obligations under non-cancelable ground leases by year as of December 31, 2018, and for each of the next four years ending December 31 and thereafter, are as follows (amounts in thousands):
Year
 
Amount
2019
 
$
123

2020
 
123

2021
 
123

2022
 
123

2023
 
123

Thereafter
 
2,246

Total undiscounted rental payments
 
$
2,861

This table excludes future lease payment obligations from one tenant that pays the ground lease obligations directly to the lessor, consistent with the Company's accounting policy prior to its adoption of ASC 842 on January 1, 2019.
The future minimum rent obligations under non-cancelable ground leases as of December 31, 2018, for each of the next five years ended December 31 and thereafter, are as follows (amounts in thousands):
Year
 
Amount
2019
 
$
123

2020
 
123

2021
 
123

2022
 
123

2023
 
123

Thereafter
 
2,246

 
 
$
2,861