Financial Instruments and Fair Values - Summary of the Carrying and Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in accounts payable and accrued expenses	$ 30,387	$ 13,330
Ground lease liabilities	29,256	29,307
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Ground lease liabilities	29,256	29,307
Carrying Value | Mortgage notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	604,763	605,542
Carrying Value | Senior notes | Senior unsecured notes - Series A, B, C, D, E, F, G and H
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	973,002
Carrying Value | Senior notes | Senior unsecured notes - Series A, B, C, D, E and F
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value		798,392
Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Ground lease liabilities	34,564	33,790
Estimated Fair Value | Mortgage notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	638,852	629,609
Estimated Fair Value | Senior notes | Senior unsecured notes - Series A, B, C, D, E, F, G and H
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	1,034,848
Estimated Fair Value | Senior notes | Senior unsecured notes - Series A, B, C, D, E and F
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value		843,394
Level 1 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Ground lease liabilities	0	0
Level 1 | Estimated Fair Value | Mortgage notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Level 1 | Estimated Fair Value | Senior notes | Senior unsecured notes - Series A, B, C, D, E, F, G and H
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0
Level 1 | Estimated Fair Value | Senior notes | Senior unsecured notes - Series A, B, C, D, E and F
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value		0
Level 2 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Ground lease liabilities	0	0
Level 2 | Estimated Fair Value | Mortgage notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Level 2 | Estimated Fair Value | Senior notes | Senior unsecured notes - Series A, B, C, D, E, F, G and H
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0
Level 2 | Estimated Fair Value | Senior notes | Senior unsecured notes - Series A, B, C, D, E and F
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value		0
Level 3 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Ground lease liabilities	34,564	33,790
Level 3 | Estimated Fair Value | Mortgage notes payable
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	638,852	629,609
Level 3 | Estimated Fair Value | Senior notes | Senior unsecured notes - Series A, B, C, D, E, F, G and H
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	1,034,848
Level 3 | Estimated Fair Value | Senior notes | Senior unsecured notes - Series A, B, C, D, E and F
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value		843,394
Unsecured term loan facility | Carrying Value | Unsecured term loan facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	386,568	264,640
Unsecured term loan facility | Carrying Value | Unsecured revolving credit facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	546,436
Unsecured term loan facility | Estimated Fair Value | Unsecured term loan facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	391,627	265,000
Unsecured term loan facility | Estimated Fair Value | Unsecured revolving credit facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	550,000
Unsecured term loan facility | Level 1 | Estimated Fair Value | Unsecured term loan facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Unsecured term loan facility | Level 1 | Estimated Fair Value | Unsecured revolving credit facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0
Unsecured term loan facility | Level 2 | Estimated Fair Value | Unsecured term loan facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0	0
Unsecured term loan facility | Level 2 | Estimated Fair Value | Unsecured revolving credit facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	0
Unsecured term loan facility | Level 3 | Estimated Fair Value | Unsecured term loan facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	391,627	265,000
Unsecured term loan facility | Level 3 | Estimated Fair Value | Unsecured revolving credit facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, fair value	550,000
Interest Rate Swap
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in accounts payable and accrued expenses	30,800
Interest Rate Swap | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in accounts payable and accrued expenses	30,387	13,330
Interest Rate Swap | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in accounts payable and accrued expenses	30,387	13,330
Interest Rate Swap | Level 1 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in accounts payable and accrued expenses	0	0
Interest Rate Swap | Level 2 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in accounts payable and accrued expenses	30,387	13,330
Interest Rate Swap | Level 3 | Estimated Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate swaps included in accounts payable and accrued expenses	$ 0	$ 0