Debt - Notes - Summary of Notes Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Notes, net beginning balance	$ 5,933,286	$ 5,038,812
Proceeds	1,194,468	896,294	$ 692,466
Lump sum payoffs	(1,050,000)		(497,975)
Realized/unrealized (gain) loss on derivative instruments	2,277	(680)	(3,454)
Amortization of premiums/ discounts	3,162	2,637	2,364
Amortization of deferred financing costs, net	(5,680)	(3,777)
Notes, net ending balance	6,077,513	5,933,286	5,038,812
Fixed Rate Debt [Member] | Unsecured – Public [Member]
Debt Instrument [Line Items]
Notes, net beginning balance	5,485,884	4,591,373
Proceeds	1,194,468	896,294
Lump sum payoffs	(600,000)
Amortization of premiums/ discounts	3,117	2,547
Amortization of deferred financing costs, net	(5,956)	(4,330)
Notes, net ending balance	6,077,513	5,485,884	4,591,373
Floating Rate Debt [Member] | Unsecured – Public [Member]
Debt Instrument [Line Items]
Notes, net beginning balance	447,402	447,439
Lump sum payoffs	(450,000)
Realized/unrealized (gain) loss on derivative instruments	2,277	(680)
Amortization of premiums/ discounts	45	90
Amortization of deferred financing costs, net	$ 276	553
Notes, net ending balance		$ 447,402	$ 447,439