Derivative Financial Instruments - Impact of Derivatives on Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Cash Flow Hedges
Interest expense	$ 117,811	$ 185,326	$ 428,649	$ 526,352
Trading
Total	5,820	656	58,965	17,331
Designated as Hedging Instrument
Fair Value Hedges
Interest recognized on derivatives	23,851	(2,924)	47,906	(10,812)
Hedged items recorded in interest expense	24,451	(16,391)	(116,500)	(98,094)
Derivatives recorded in interest expense	(24,458)	16,610	116,870	97,947
Trading
Total	23,844	(2,705)	48,276	(10,959)
Designated as Hedging Instrument | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | Reclassification out of Accumulated Other Comprehensive Income
Cash Flow Hedges
Interest expense	(5,176)	517	(10,922)	3,002
Trading
Trading
Change in fair value of future interest payments recorded in earnings	(12,848)	2,844	21,611	25,288
Total	$ (12,848)	$ 2,844	$ 21,611	$ 25,288