Derivative Financial Instruments - Notional Values (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Derivatives, Fair Value [Line Items]
Notional values	$ 8,800,000
Interest rate swaps
Derivatives, Fair Value [Line Items]
Notional values	8,790,662	$ 9,926,864
Interest rate swaps | Trading
Derivatives, Fair Value [Line Items]
Notional values	2,693,364	3,744,917
Interest rate swaps | Cash Flow Hedges | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional values	1,052,164	1,150,518
Interest rate swaps | Fair Value Hedges | Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Notional values	$ 5,045,134	$ 5,031,429