Derivative Financial Instruments (Schedule of Derivative Instruments in Statement of Financial Position, Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Derivative Asset, Fair Value, Subject to a Master Netting Agreement	$ 8,992	$ 35,727
Derivative Asset, Collateral, Obligation to Return Cash, Offset	32,000
Derivative Asset	43	0
Derivative Liability, Fair Value, Subject to a Master Netting Agreement	2,387	25,300
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	35,100
Derivative Liability	142	446
Loan Origination Commitments [Member]
Derivative [Line Items]
Other Commitment	39,000
Interest Rate Lock Commitments [Member]
Derivative [Line Items]
Other Commitment	11,300
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Subject to a Master Netting Agreement	2,770	3,270
Derivative Asset, Fair Value, Amount Offset Against Collateral	91	2,335
Derivative Asset, Collateral, Obligation to Return Cash, Offset	2,679	935
Derivative Asset	0	0
Derivative Liability, Fair Value, Subject to a Master Netting Agreement	0	792
Derivative Liability, Fair Value, Amount Offset Against Collateral	0	792
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	0
Derivative Liability	0	0
Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Subject to a Master Netting Agreement	6,222	32,457
Derivative Asset, Fair Value, Amount Offset Against Collateral	2,154	21,917
Derivative Asset, Collateral, Obligation to Return Cash, Offset	4,025	10,540
Derivative Asset	43	0
Derivative Liability, Fair Value, Subject to a Master Netting Agreement	2,387	24,508
Derivative Liability, Fair Value, Amount Offset Against Collateral	2,245	23,462
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	600
Derivative Liability	142	446
Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member] | Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	325,000	225,000
Derivative Asset, Fair Value, Subject to a Master Netting Agreement	2,770	3,270
Derivative Liability, Notional Amount	0	100,000
Derivative Liability, Fair Value, Subject to a Master Netting Agreement	0	792
Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	2,791,760	1,943,485
Derivative Asset, Fair Value, Subject to a Master Netting Agreement	5,977	32,226
Derivative Liability, Notional Amount	721,048	1,242,937
Derivative Liability, Fair Value, Subject to a Master Netting Agreement	1,968	24,388
Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Other Contract [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	7,914	10,634
Derivative Asset, Fair Value, Subject to a Master Netting Agreement	258	231
Derivative Liability, Notional Amount	30,328	14,265
Derivative Liability, Fair Value, Subject to a Master Netting Agreement	419	120
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	4,288,183	3,879,713
Derivative Asset, Fair Value, Not Subject to Master Netting Agreement	29,745	74,367
Derivative Liability, Notional Amount	3,056,079	2,856,313
Derivative Liability, Fair Value, Not Subject to Master Netting Agreement	28,423	44,397
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Interest Rate Contract [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	1,366,299	1,734,679
Derivative Asset, Fair Value, Not Subject to Master Netting Agreement	23,009	38,668
Derivative Liability, Notional Amount	2,146,518	1,451,762
Derivative Liability, Fair Value, Not Subject to Master Netting Agreement	25,631	19,001
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Credit Risk Contract [Member] | Credit Default Swap, Buying Protection [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	93,713	86,037
Derivative Asset, Fair Value, Not Subject to Master Netting Agreement	80	139
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Credit Risk Contract [Member] | Credit Default Swap, Selling Protection [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	116,882	87,273
Derivative Liability, Fair Value, Not Subject to Master Netting Agreement	111	166
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Other Contract [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	0	1,438
Derivative Asset, Fair Value, Not Subject to Master Netting Agreement	0	19
Derivative Liability, Notional Amount	2,073	181
Derivative Liability, Fair Value, Not Subject to Master Netting Agreement	184	11
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Mortgage Banking Derivatives [Member] | Credit Default Swap, Buying Protection [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	28,497	103,440
Derivative Asset, Fair Value, Not Subject to Master Netting Agreement	421	3,084
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] | Not Designated as Hedging Instrument [Member] | Mortgage Banking Derivatives [Member] | Credit Default Swap, Selling Protection [Member]
Derivative [Line Items]
Derivative Liability, Notional Amount	39,230	59,895
Derivative Liability, Fair Value, Not Subject to Master Netting Agreement	110	711
Subject to and not subject to Master Netting Agreements [Member]
Derivative [Line Items]
Derivative Asset, Notional Amount	4,613,183	4,104,713
Derivative Asset, Fair Value, Gross derivative instruments, before netting	32,515	77,637
Derivative Asset, Fair Value, Amount Offset Against Collateral	2,245	24,252
Derivative Asset, Collateral, Obligation to Return Cash, Offset	6,704	11,475
Derivative Asset	23,566	41,910
Derivative Liability, Notional Amount	3,056,079	2,956,313
Derivative Liability, Fair Value, Gross derivative instruments, before netting	28,423	45,189
Derivative Liability, Fair Value, Amount Offset Against Collateral	2,245	24,254
Derivative Liability, Collateral, Right to Reclaim Cash, Offset	0	600
Derivative Liability	$ 26,178	$ 20,335