Fair Value Measurements and Disclosures - Financial Instruments Disclosed at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Carrying value [Member] | Secured debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	$ 253,582	$ 258,593
Carrying value [Member] | Unsecured debt [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	3,670,099	3,049,185
Carrying value [Member] | Unsecured line of credit [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	0	245,000
Fair value [Member] | Secured debt [Member] | Fair value (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	282,559	272,997
Fair value [Member] | Unsecured debt [Member] | Fair value (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	4,089,339	3,252,217
Fair value [Member] | Unsecured line of credit [Member] | Fair value (Level 2) [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt instrument, fair value disclosure	$ 0	$ 245,195