Financial Derivatives Derivatives in Fair Value and Cash Flow Hedging Relationships (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Line Items Presented in the Consolidated Statement of Income [Abstract]
Interest Income, Operating	$ 76,870	$ 54,350	$ 213,479	$ 146,978
Interest and Fee Income, Loans and Leases	50,622	40,924	145,671	117,349
Total interest expense	(97,557)	(64,935)	(265,611)	(172,797)
Gain (Loss) on Derivative Instruments, Net, Pretax	(628)	(661)	688	(2,530)
TotalAmountsofLineItemsPresentedintheConsolidatedStatementofIncome	30,563	31,000	92,851	94,060
Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	1,051	1,742	5,751	(716)
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness		(191)		(365)
Income_Expense related to interest settlements on fair value hedges	6,903	5,851	16,331	16,253
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative	16,141	1,576	45,353	(5,466)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	(15,090)	166	(39,602)	4,750
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Premium_Discount recognized on hedged item	(2)	(1)	(5)	(3)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	189	(454)	(21)	(1,494)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	(2,501)	(1,169)	(6,611)	(2,665)
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	(2,314)	(1,815)	(6,637)	(4,527)
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Item Net Interest Settlements	8,608	7,864	22,275	23,425
Premium_Discount recognized on hedged item	(177)	(121)	(534)	(311)
Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax		890		(3,611)
Interest Income [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	0		0
Interest Income [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	(12)	0	3,125	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	(13,432)	0	(43,229)	0
Interest Income [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Premium_Discount recognized on hedged item	0	0	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0	0	0	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	0	0	0	0
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	0	0	0	0
Interest Income [Member] | Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Item Net Interest Settlements	16,769	11,986	46,289	34,212
Premium_Discount recognized on hedged item	0	0	0	0
Interest Income [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax		0		0
Loans and Finance Receivables [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	0		0
Loans and Finance Receivables [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	(153)	0	(542)	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	(4,062)	0	(13,106)	0
Loans and Finance Receivables [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Premium_Discount recognized on hedged item	0	0	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0	0	0	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	0	0	0	0
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	0	0	0	0
Loans and Finance Receivables [Member] | Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Item Net Interest Settlements	1,660	947	4,619	2,045
Premium_Discount recognized on hedged item	0	0	0	0
Loans and Finance Receivables [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax		0		0
Interest Expense [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	0
Interest Expense [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	1,216	0	3,168	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	2,404	0	16,733	0
Interest Expense [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Premium_Discount recognized on hedged item	(2)	(1)	(5)	(3)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	189	(454)	(21)	(1,494)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	(2,501)	(1,169)	(6,611)	(2,665)
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	(2,314)	(1,624)	(6,637)	(4,162)
Interest Expense [Member] | Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Item Net Interest Settlements	(9,821)	(5,069)	(28,633)	(12,832)
Premium_Discount recognized on hedged item	(177)	(121)	(534)	(311)
Interest Expense [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax		0	0	0
Gain (Loss) on Derivative Instruments [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	(628)	890	688	(3,611)
Gain (Loss) on Derivative Instruments [Member] | Fair Value Hedging [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Derivative Net Interest Settlements	0	0	0	0
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	0	1,742	0	(716)
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness		(191)		(365)
Income_Expense related to interest settlements on fair value hedges	0	0	0	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative	0	1,576	0	(5,466)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	0	166	0	4,750
Gain (Loss) on Derivative Instruments [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Premium_Discount recognized on hedged item	0	0	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	0	0	0	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	0	0	0	0
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	0	(191)	0	(365)
Gain (Loss) on Derivative Instruments [Member] | Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Item Net Interest Settlements	0	0	0	0
Premium_Discount recognized on hedged item	0	0	0	0
Interest Rate Swap [Member] | Fair Value Hedging [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Derivative Net Interest Settlements	(1,528)	(1,892)	(5,410)	(6,861)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Components Included from Assessment of Interest Rate Fair Value Hedge Effectiveness		(1,600)		700
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net		100		0
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Total interest expense	(3,048)	(2,676)	(8,903)	(8,318)
Gain (Loss) on Derivative Instruments, Net, Pretax	(3,267)	(1,645)	(7,443)	(12,324)
Interest Rate Swap [Member] | Interest Income [Member] | Fair Value Hedging [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Derivative Net Interest Settlements	1,272	(2,267)	465	(8,251)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness		0		0
Income_Expense related to interest settlements on fair value hedges	18,041	9,719	46,754	25,961
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative	13,420	0	46,354	0
Interest Rate Swap [Member] | Interest Income [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Total interest expense	0	0	0	0
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Interest Rate Swap [Member] | Loans and Finance Receivables [Member] | Fair Value Hedging [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Derivative Net Interest Settlements	(98)	(342)	(560)	(767)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness		0		0
Income_Expense related to interest settlements on fair value hedges	1,562	605	4,059	1,278
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative	3,909	0	12,564	0
Interest Rate Swap [Member] | Loans and Finance Receivables [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Total interest expense	0	0	0	0
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Interest Rate Swap [Member] | Interest Expense [Member] | Fair Value Hedging [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Derivative Net Interest Settlements	(2,702)	717	(5,315)	2,157
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness		0		0
Income_Expense related to interest settlements on fair value hedges	(12,700)	(4,473)	(34,482)	(10,986)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative	(1,188)	0	(13,565)	0
Interest Rate Swap [Member] | Interest Expense [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Total interest expense	0	0	0	0
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Interest Rate Swap [Member] | Gain (Loss) on Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Total interest expense	(3,048)	(2,676)	(8,903)	(8,318)
Gain (Loss) on Derivative Instruments, Net, Pretax	(3,267)	(1,645)	(7,443)	(12,324)
Forward Contracts [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax		0		588
Forward Contracts [Member] | Interest Income [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax		0		0
Forward Contracts [Member] | Loans and Finance Receivables [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax		0		0
Forward Contracts [Member] | Interest Expense [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax		0		0
Forward Contracts [Member] | Gain (Loss) on Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax		0		588
Future [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	(409)	(141)	(772)	(193)
Future [Member] | Interest Income [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Future [Member] | Loans and Finance Receivables [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Future [Member] | Interest Expense [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	0	0	0	0
Future [Member] | Gain (Loss) on Derivative Instruments [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	$ (409)	$ (141)	$ (772)	$ (193)