Derivative Financial Instruments - Impact of Derivatives on Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Cash Flow Hedges
Interest expense	$ 164,172	$ 104,617
Trading
Total	1,573	(426)
Designated as Hedging Instrument
Fair Value Hedges
Interest recognized on derivatives	(3,827)	5,853
Hedged items recorded in interest expense	(23,986)	15,265
Derivatives recorded in interest expense	23,888	(15,246)
Trading
Total	(3,925)	5,872
Trading
Trading
Change in fair value of future interest payments recorded in earnings	4,202	(4,755)
Total	4,202	(4,755)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent \| Reclassification out of Accumulated Other Comprehensive Income \| Designated as Hedging Instrument
Cash Flow Hedges
Interest expense	$ 1,296	$ (1,543)

Derivative Instruments Increase (Decrease) In Fair Value Of Future Interest Payments Recorded In Earnings

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Amount of gain (loss) from the increase (decrease) in fair value of derivative and nonderivative instruments designated as fair value hedging instruments recognized in the income statement.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period.

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Amount of the cost of borrowed funds accounted for as interest expense.

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