Derivative Financial Instruments - Impact of Derivatives on Consolidated Statements of Income (Details) - Interest rate swaps - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Trading
Gain (loss) on derivatives, net	$ (3,397)	$ 4,947	$ (7,567)	$ 7,231
Designated as Hedging Instrument \| Fair Value Hedges
Fair Value Hedges
Hedge ineffectiveness gains (losses) recorded in earnings	(3,711)	1,218	(7,878)	(1,199)
Realized gains (losses) recorded in interest expense	2,881	7,391	7,428	14,650
Trading
Gain (loss) on derivatives, net	(830)	8,609	(450)	13,451
Designated as Hedging Instrument \| Cash Flow Hedges
Cash Flow Hedges
Hedge ineffectiveness losses recorded in earnings	(75)	(403)	(147)	(681)
Realized losses recorded in interest expense	(2,669)	(4,586)	(6,008)	(9,207)
Trading
Gain (loss) on derivatives, net	(2,744)	(4,989)	(6,155)	(9,888)
Trading
Trading
Interest reclassification	(101)	672	(20)	1,360
Realized gains (losses) recorded in earnings	278	655	(942)	2,308
Gain (loss) on derivatives, net	$ 177	$ 1,327	$ (962)	$ 3,668

Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net, Hedge Ineffectiveness

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Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net, Interest Reclassification

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5618551-113959

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The net gain (loss) relating to components of the gain (loss) on the cash flow hedging instrument excluded from the assessment of cash flow hedge effectiveness. Recognized in earnings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Net gain (loss) relating to components of the gain (loss) on the fair value hedging instrument excluded from the assessment of fair value hedge effectiveness. Recognized in earnings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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The net gain (loss) recognized in earnings during the reporting period representing the amount of the cash flow hedges' ineffectiveness.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Amount of gain (loss)recognized in the income statement from the hedging ineffectiveness of a fair value hedge.

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