Loans and Allowances for Credit Losses, Troubled Debt Restructurings (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	$ 119,871	$ 109,335	$ 119,871	$ 109,335	$ 106,281
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	48,994	40,198	48,994	40,198	42,343
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	70,877	69,137	70,877	69,137	63,938
Troubled Debt Restructuring, Specific allowance	3,293	420	3,293	420	441
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	159	290	305	1,492
Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	49,412	59,236	49,412	59,236	51,959
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	25,996	28,223	25,996	28,223	28,959
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	23,416	31,013	23,416	31,013	23,000
Troubled Debt Restructuring, Specific allowance	3,293	420	3,293	420	441
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	159	290	305	1,492
Commercial [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	9,258	5,234	9,258	5,234	3,632
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	4,567	1,445	4,567	1,445	1,114
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	4,691	3,789	4,691	3,789	2,518
Troubled Debt Restructuring, Specific allowance	3,157	259	3,157	259	246
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	154	0	154
Energy [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	0	0	0	0	0
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	0	0	0
Services [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	1,714	3,791	1,714	3,791	2,235
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	724	1,274	724	1,274	852
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	990	2,517	990	2,517	1,383
Troubled Debt Restructuring, Specific allowance	148	250	148	250	237
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	0	0	0
Wholesale/retail [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	3,545	275	3,545	275	235
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	3,440	141	3,440	141	89
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	105	134	105	134	146
Troubled Debt Restructuring, Specific allowance	9	9	9	9	9
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	0	0	0
Manufacturing [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	3,355	396	3,355	396	391
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	355	0	355	0	0
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	3,000	396	3,000	396	391
Troubled Debt Restructuring, Specific allowance	3,000	0	3,000	0	0
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	154	0	154
Healthcare [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	0	0	0	0	0
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	0	0	0
Other commercial and industrial [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	644	772	644	772	771
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	48	30	48	30	173
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	596	742	596	742	598
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	0	0	0
Commercial Real Estate [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	16,314	31,613	16,314	31,613	24,577
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	5,687	12,956	5,687	12,956	11,342
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	10,627	18,657	10,627	18,657	13,235
Troubled Debt Restructuring, Specific allowance	56	148	56	148	107
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	0	0	758
Residential construction and land development [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	8,562	10,673	8,562	10,673	10,148
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	264	1,776	264	1,776	1,444
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	8,298	8,897	8,298	8,897	8,704
Troubled Debt Restructuring, Specific allowance	56	148	56	148	107
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	0	0	54
Retail [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	3,664	6,030	3,664	6,030	4,359
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	2,486	2,032	2,486	2,032	3,141
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	1,178	3,998	1,178	3,998	1,218
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	0	0	627
Office [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	2,345	5,448	2,345	5,448	5,059
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	1,194	1,294	1,194	1,294	3,872
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	1,151	4,154	1,151	4,154	1,187
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	0	0	77
Multifamily [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	0	980	0	980	0
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	0	980	0	980	0
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	0	0	0
Industrial [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	0	0	0	0	0
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	0	0	0	0
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	0	0	0
Other commercial real estate [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	1,743	8,482	1,743	8,482	5,011
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	1,743	6,874	1,743	6,874	2,885
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	0	1,608	0	1,608	2,126
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	0	0	0
Residential Mortgage [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	23,366	21,101	23,366	21,101	22,742
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	15,420	12,798	15,420	12,798	15,745
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	7,946	8,303	7,946	8,303	6,997
Troubled Debt Restructuring, Specific allowance	80	13	80	13	88
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	159	134	304	577
Permanent mortage [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	16,764	17,319	16,764	17,319	18,697
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	11,227	9,579	11,227	9,579	12,214
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	5,537	7,740	5,537	7,740	6,483
Troubled Debt Restructuring, Specific allowance	80	13	80	13	88
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	147	73	246	450
Permanent mortgages guaranteed by US govenment agencies [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	1,665		1,665
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	329		329
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	1,336		1,336
Troubled Debt Restructuring, Specific allowance	0		0
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0		0
Permanent mortgages guaranteed by US govenment agencies [Member] | Accruing [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	70,459	50,099	70,459	50,099	54,322
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	22,998	11,975	22,998	11,975	13,384
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	47,461	38,124	47,461	38,124	40,938
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	0	0	0	0
Home equity {Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	4,937	3,782	4,937	3,782	4,045
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	3,864	3,219	3,864	3,219	3,531
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	1,073	563	1,073	563	514
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	12	61	58	127
Consumer [Member] | Nonaccrual [Member]
Financing Receivable, Modifications [Line Items]
Troubled Debt Restructuring, Recorded Investment	474	1,288	474	1,288	1,008
Troubled Debt Restructuring, Performing in Accordance With Modified Terms	322	1,024	322	1,024	758
Troubled Debt Restructuring, Not Performing in Accordance With Modified Terms	152	264	152	264	250
Troubled Debt Restructuring, Specific allowance	0	0	0	0	0
Financing Receivables, Impaired, Troubled Debt Restructuring, Charge-offs	$ 0	$ 2	$ 1	$ 3