Financial Derivatives Derivatives in Fair Value and Cash Flow Hedging Relationships (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Line Items Presented in the Consolidated Statement of Income [Abstract]
Interest Income, Operating									$ 290,953	$ 203,796	$ 150,281
Interest and Fee Income, Loans and Leases									198,152	162,150	134,577
Total interest expense	$ (104,237)	$ (97,557)	$ (91,737)	$ (76,317)	$ (70,088)	$ (64,935)	$ (58,316)	$ (49,546)	(369,848)	(242,885)	(171,626)
Gain (Loss) on Derivative Instruments, Net, Pretax									3,687	(753)	(2,311)
TotalAmountsofLineItemsPresentedintheConsolidatedStatementofIncome									115,570	123,814	115,543
Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Income_Expense related to interest settlements on fair value hedges									27,253	26,295	20,859
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative									(14,413)	1,694	25,365
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge									19,354	(2,413)	(20,322)
Gain (Loss) on Fair Value Hedges Recognized in Earnings									4,941	(719)	5,043
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness										(320)	(353)
Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Premium_Discount recognized on hedged item									(6)	(5)	(1)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax									316	(1,974)	(2,126)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item									(9,182)	(4,133)	(1,437)
Unrealized Gain (Loss) on Cash Flow Hedging Instruments									(8,872)	(6,432)	(3,917)
Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Item Net Interest Settlements									34,685	35,485	37,232
Premium_Discount recognized on hedged item									(668)	(345)	0
Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax										(1,792)	2,379
Interest Income [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Gain (Loss) on Derivative Instruments, Net, Pretax									0
Interest Income [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge									21,460	0	0
Gain (Loss) on Fair Value Hedges Recognized in Earnings									1,181	0	0
Interest Income [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Premium_Discount recognized on hedged item									0	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax									0	0	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item									0	0	0
Unrealized Gain (Loss) on Cash Flow Hedging Instruments									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									65,238	46,389	35,169
Premium_Discount recognized on hedged item									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
Loans and Finance Receivables [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge									(5,243)	0	0
Gain (Loss) on Fair Value Hedges Recognized in Earnings									(212)	0	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
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax									0	0	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item									0	0	0
Unrealized Gain (Loss) on Cash Flow Hedging Instruments									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									6,284	3,379	2,063
Premium_Discount recognized on hedged item									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]
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge									3,137	0	0
Gain (Loss) on Fair Value Hedges Recognized in Earnings									3,972	0	0
Interest Expense [Member] | Cash Flow Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Premium_Discount recognized on hedged item									(6)	(5)	(1)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax									316	(1,974)	(2,126)
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item									(9,182)	(4,133)	(1,437)
Unrealized Gain (Loss) on Cash Flow Hedging Instruments									(8,872)	(6,112)	(3,564)
Interest Expense [Member] | Designated as Hedging Instrument [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Item Net Interest Settlements									(36,837)	(14,283)	0
Premium_Discount recognized on hedged item									(668)	(345)	0
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									3,687	(1,792)	2,379
Gain (Loss) on Derivative Instruments [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Net Interest Settlements									0	0	0
Income_Expense related to interest settlements on fair value hedges									0	0	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative									0	1,694	25,365
Change in Unrealized Gain (Loss) on Hedged Item in Fair Value Hedge									0	(2,413)	(20,322)
Gain (Loss) on Fair Value Hedges Recognized in Earnings									0	(719)	5,043
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness										(320)	(353)
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
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax									0	0	0
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Hedged Item									0	0	0
Unrealized Gain (Loss) on Cash Flow Hedging Instruments									0	(320)	(353)
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
Premium_Discount recognized on hedged item									0	0	0
Interest Rate Swap [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Net Interest Settlements									(6,764)	(8,845)	(16,373)
Gain (Loss) on Components Included from Assessment of Interest Rate Fair Value Hedge Effectiveness										100	(5,200)
Gain (Loss) on Fair Value Hedge Ineffectiveness, Net										(600)	(200)
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Line Items Presented in the Consolidated Statement of Income [Abstract]
Total interest expense									(10,920)	(10,200)	(11,480)
Gain (Loss) on Derivative Instruments, Net, Pretax									(7,206)	(12,240)	(9,489)
Interest Rate Swap [Member] | Interest Income [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Net Interest Settlements									1,861	(10,346)	(15,494)
Income_Expense related to interest settlements on fair value hedges									67,099	36,043	19,675
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative									(20,279)	0	0
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness										0	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
Gain (Loss) on Derivative Instruments, Net, Pretax									0	0	0
Interest Rate Swap [Member] | Loans and Finance Receivables [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Net Interest Settlements									(630)	(1,141)	(1,011)
Income_Expense related to interest settlements on fair value hedges									5,654	2,238	1,052
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative									5,031	0	0
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness										0	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
Gain (Loss) on Derivative Instruments, Net, Pretax									0	0	0
Interest Rate Swap [Member] | Interest Expense [Member] | Fair Value Hedging [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Net Interest Settlements									(7,995)	2,642	132
Income_Expense related to interest settlements on fair value hedges									(45,500)	(11,986)	132
Derivative Net Hedge Ineffectiveness Gain Loss Component Recognized On Derivative									835	0	0
Gain (Loss) on Interest Rate Cash Flow Hedge Ineffectiveness										0	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
Gain (Loss) on Derivative Instruments, Net, Pretax									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									(10,920)	(10,200)	(11,480)
Gain (Loss) on Derivative Instruments, Net, Pretax									(7,206)	(12,240)	(9,489)
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										588	226
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										588	226
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									(27)	(340)	162
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
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
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
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									$ (27)	$ (340)	$ 162