Derivative Financial Instruments - Notional Values (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Notional Values	$ 9,900,000
Interest Rate Swaps
Derivative Instruments, Gain (Loss) [Line Items]
Notional Values	9,926,864	$ 5,996,310
Interest Rate Swaps | Trading
Derivative Instruments, Gain (Loss) [Line Items]
Notional Values	3,744,917	1,577,978
Interest Rate Swaps | Cash Flow | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional Values	1,150,518	1,280,367
Interest Rate Swaps | Fair Value | Designated as Hedging Instrument
Derivative Instruments, Gain (Loss) [Line Items]
Notional Values	$ 5,031,429	$ 3,137,965