Financial Derivatives Derivatives in Fair Value and Cash Flow Hedging Relationships (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Line Items Presented in the Consolidated Statement of Income [Abstract]
Interest Income, Operating	$ 74,179	$ 50,106	$ 136,609	$ 92,628
Interest and Fee Income, Loans and Leases	49,396	39,573	95,049	76,425
Total interest expense	(91,737)	(58,316)	(168,054)	(107,862)
Gain (Loss) on Derivative Instruments, Net, Pretax	(2,534)	617	1,316	(1,869)
TotalAmountsofLineItemsPresentedintheConsolidatedStatementofIncome	34,372	30,746	62,288	63,060
Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	1,862	1,420	4,701	(2,457)
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness		(146)		(175)
Income_Expense related to interest settlements on fair value hedges	5,402	5,263	9,503	10,402
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative	11,989	(8,568)	29,212	(7,041)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	(10,127)	9,988	(24,511)	4,584
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Premium_Discount recognized on hedged item	(2)	(1)	(4)	(2)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	57	(497)	(210)	(1,040)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	(2,330)	(845)	(4,110)	(1,496)
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	(2,275)	(1,489)	(4,324)	(2,713)
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Item Net Interest Settlements	7,394	7,160	13,740	15,561
Premium_Discount recognized on hedged item	(188)	(120)	(353)	(190)
Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax		1,891		(4,501)
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	1,636	0	3,137	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	(10,849)	0	(29,797)	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	15,923	11,633	29,409	22,226
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	(237)	0	(390)	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	(2,472)	0	(9,045)	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	1,545	583	2,959	1,099
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		0
Interest Expense [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	463	0	1,954	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	3,194	0	14,331	0
Interest Expense [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Premium_Discount recognized on hedged item	(2)	(1)	(4)	(2)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	57	(497)	(210)	(1,040)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	(2,330)	(845)	(4,110)	(1,496)
Unrealized Gain (Loss) on Cash Flow Hedging Instruments	(2,275)	(1,343)	(4,324)	(2,538)
Interest Expense [Member] | Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Item Net Interest Settlements	(10,074)	(5,056)	(18,628)	(7,764)
Premium_Discount recognized on hedged item	(188)	(120)	(353)	(190)
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
Gain (Loss) on Derivative Instruments [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	(2,534)	1,891	1,316	(4,501)
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	1,420	0	(2,457)
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness		(146)		(175)
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	(8,568)	0	(7,041)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item	0	9,988	0	4,584
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	(146)	0	(175)
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	(1,804)	(1,777)	(3,884)	(4,969)
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Components Included from Assessment of Interest Rate Fair Value Hedge Effectiveness		(1,300)		2,300
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net		100		(100)
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax	(2,396)	1,648	1,679	(5,036)
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	681	(2,826)	(807)	(5,984)
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	16,604	8,807	28,602	16,242
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative	12,485	0	32,934	0
Interest Rate Swap [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
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	(165)	(208)	(463)	(425)
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	1,380	375	2,496	674
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative	2,235	0	8,655	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]
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	(2,320)	1,257	(2,614)	1,440
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	(12,582)	(3,919)	(21,595)	(6,514)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative	(2,731)	0	(12,377)	0
Interest Rate Swap [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
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]
Gain (Loss) on Derivative Instruments, Net, Pretax	(2,396)	1,648	1,679	(5,036)
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		189		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		189		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	(138)	54	(363)	(53)
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	$ (138)	$ 54	$ (363)	$ (53)