Equity - Changes to Accumulated Other Comprehensive Income (Loss) by Component (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Net unrealized gains (losses) on our Level 3 AFS securities	$ 8,000		$ (16,000)
Balance at beginning of period	936,576	$ 1,564,032	1,827,231	$ 1,348,794
Total other comprehensive income (loss)	8,831	(10,799)	(62,073)	(23,173)
Balance at End of Period	1,053,464	1,785,059	1,053,464	1,785,059
Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	53,246	98,307	92,452	95,342
Other comprehensive income (loss) before reclassifications	8,236	4,484	(19,890)	19,764
Amounts reclassified from other accumulated comprehensive income	(445)	(3,492)	(11,525)	(15,807)
Total other comprehensive income (loss)	7,791	992	(31,415)	3,957
Balance at End of Period	61,037	99,299	61,037	99,299
Interest Rate Agreements Accounted for as Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at beginning of period	(82,637)	(49,384)	(50,939)	(34,045)
Other comprehensive income (loss) before reclassifications	0	(11,791)	(32,806)	(27,130)
Amounts reclassified from other accumulated comprehensive income	1,040	0	2,148	0
Total other comprehensive income (loss)	1,040	(11,791)	(30,658)	(27,130)
Balance at End of Period	$ (81,597)	$ (61,175)	$ (81,597)	$ (61,175)