Derivative Financial Instruments - Impact of Derivatives on Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Cash Flow Hedges
Interest expense	$ 185,326	$ 140,964	$ 526,352	$ 366,942
Trading
Total	656	(5,642)	17,331	(18,185)
Designated as Hedging Instrument
Fair Value Hedges
Interest recognized on derivatives	(2,924)	(3,977)	(10,812)	(7,303)
Hedged items recorded in interest expense	(16,391)	4,809	(98,094)	27,526
Derivatives recorded in interest expense	16,610	(4,896)	97,947	(27,774)
Trading
Total	(2,705)	(4,064)	(10,959)	(7,551)
Designated as Hedging Instrument | Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent | Reclassification out of Accumulated Other Comprehensive Income
Cash Flow Hedges
Interest expense	517	(21)	3,002	(2,142)
Trading
Trading
Change in fair value of future interest payments recorded in earnings	2,844	(1,557)	25,288	(8,492)
Total	$ 2,844	$ (1,557)	$ 25,288	$ (8,492)