Derivative Financial Instruments - Notional Values (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Notional values	$ 9,800,000
Interest rate swaps
Derivatives, Fair Value [Line Items]
Notional values	9,763,509	$ 9,926,864
Interest rate swaps | Trading
Derivatives, Fair Value [Line Items]
Notional values	3,452,241	3,744,917
Interest rate swaps | Cash Flow Hedges | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional values	1,117,945	1,150,518
Interest rate swaps | Fair Value Hedges | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional values	$ 5,193,323	$ 5,031,429