Derivative Financial Instruments - Notional Values (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Notional values	$ 8,600,000
Interest rate swaps
Derivatives, Fair Value [Line Items]
Notional values	8,566,736	$ 8,557,883
Interest rate swaps | Trading
Derivatives, Fair Value [Line Items]
Notional values	2,393,364	2,693,364
Interest rate swaps | Cash Flow Hedges | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional values	1,535,718	1,018,976
Interest rate swaps | Fair Value Hedges | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional values	$ 4,637,654	$ 4,845,543