Allowance for Loan and Lease Losses (Allocation of Allowance for Loan and Lease Losses) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013		Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		$ 0	$ 0	$ 7,368	[1]
Unpaid principal balance		1,693,372	2,057,691
Allowance for loan and lease losses		206,216	204,466	233,394		$ 319,018
Noncommercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		7,368
Noncommercial | Non-specific
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification		(15,772)
Non-PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	[1]			7,368
Unpaid principal balance		167,966	133,466
ALLL for loans and leases individually evaluated for impairment		7,200	15,717
Impaired Financing Receivable, with Related Allowance, Recorded Investment		66,861	87,007
Impaired Financing Receivable, with No Related Allowance, Recorded Investment		83,506	32,586
Financing Receivable, Individually Evaluated for Impairment		150,367	119,593
Average balance		136,404	127,421	151,330
Interest income recognized		4,675	5,427	7,817
Allowance for loan and lease losses		189,904	182,837	179,874		179,046
Non-PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	[1]			(815)
Unpaid principal balance		863	913
ALLL for loans and leases individually evaluated for impairment		289	112
Impaired Financing Receivable, with Related Allowance, Recorded Investment		305	112
Impaired Financing Receivable, with No Related Allowance, Recorded Investment		122	472
Financing Receivable, Individually Evaluated for Impairment		427	584
Average balance		481	2,125	2,658
Interest income recognized		12	80	144
Allowance for loan and lease losses		2,168	732	1,009		2,059
Non-PCI Loans | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	[1]			5,141
Unpaid principal balance		4,428	6,945
ALLL for loans and leases individually evaluated for impairment		123	92
Impaired Financing Receivable, with Related Allowance, Recorded Investment		1,623	996
Impaired Financing Receivable, with No Related Allowance, Recorded Investment		1,471	624
Financing Receivable, Individually Evaluated for Impairment		3,094	1,620
Average balance		3,164	1,689	6,414
Interest income recognized		146	83	270
Allowance for loan and lease losses		16,288	11,961	10,335		6,031
Non-PCI Loans | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	[1]			27,421
Unpaid principal balance		103,763	87,702
ALLL for loans and leases individually evaluated for impairment		3,370	8,610
Impaired Financing Receivable, with Related Allowance, Recorded Investment		41,793	57,324
Impaired Financing Receivable, with No Related Allowance, Recorded Investment		53,314	25,479
Financing Receivable, Individually Evaluated for Impairment		95,107	82,803
Average balance		89,934	86,250	105,628
Interest income recognized		3,129	3,698	5,702
Allowance for loan and lease losses		69,896	85,189	100,257		80,229
Non-PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	[1]			7,551
Unpaid principal balance		21,455	12,197
ALLL for loans and leases individually evaluated for impairment		1,118	1,743
Impaired Financing Receivable, with Related Allowance, Recorded Investment		8,544	10,319
Impaired Financing Receivable, with No Related Allowance, Recorded Investment		9,366	721
Financing Receivable, Individually Evaluated for Impairment		17,910	11,040
Average balance		14,587	13,433	12,772
Interest income recognized		510	580	642
Allowance for loan and lease losses		43,116	30,727	22,362		14,050
Non-PCI Loans | Commercial | Lease financing
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	[1]			(253)
Unpaid principal balance		1,956	623
ALLL for loans and leases individually evaluated for impairment		213	150
Impaired Financing Receivable, with Related Allowance, Recorded Investment		1,651	319
Impaired Financing Receivable, with No Related Allowance, Recorded Investment		104	304
Financing Receivable, Individually Evaluated for Impairment		1,755	623
Average balance		1,718	774	350
Interest income recognized		74	44	22
Allowance for loan and lease losses		5,524	4,286	4,749		3,521
Non-PCI Loans | Commercial | Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	[1]			(1,288)
Unpaid principal balance		1,260	2,000
ALLL for loans and leases individually evaluated for impairment		0	1,972
Impaired Financing Receivable, with Related Allowance, Recorded Investment		0	2,000
Impaired Financing Receivable, with No Related Allowance, Recorded Investment		1,183	0
Financing Receivable, Individually Evaluated for Impairment		1,183	2,000
Average balance		1,673	528	0
Interest income recognized		37	29	0
Allowance for loan and lease losses		1,855	3,184	190		1,175
Non-PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	[1]			(478)
Unpaid principal balance		784	1,340
ALLL for loans and leases individually evaluated for impairment		49	71
Impaired Financing Receivable, with Related Allowance, Recorded Investment		693	1,077
Impaired Financing Receivable, with No Related Allowance, Recorded Investment		91	263
Financing Receivable, Individually Evaluated for Impairment		784	1,340
Average balance		829	1,678	958
Interest income recognized		38	98	55
Allowance for loan and lease losses		1,485	892	681		1,721
Non-PCI Loans | Noncommercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	[1]			5,717
Unpaid principal balance		25,043	15,746
ALLL for loans and leases individually evaluated for impairment		1,212	1,360
Impaired Financing Receivable, with Related Allowance, Recorded Investment		10,097	10,198
Impaired Financing Receivable, with No Related Allowance, Recorded Investment		12,889	4,715
Financing Receivable, Individually Evaluated for Impairment		22,986	14,913
Average balance		18,524	15,487	15,470
Interest income recognized		557	593	444
Allowance for loan and lease losses		14,105	10,661	10,511		3,836
Non-PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	[1]			(9,838)
Unpaid principal balance		7,120	4,933
ALLL for loans and leases individually evaluated for impairment		299	1,052
Impaired Financing Receivable, with Related Allowance, Recorded Investment		1,105	3,675
Impaired Financing Receivable, with No Related Allowance, Recorded Investment		4,778	0
Financing Receivable, Individually Evaluated for Impairment		5,883	3,675
Average balance		4,368	3,922	5,653
Interest income recognized		97	134	485
Allowance for loan and lease losses		15,971	18,650	16,239		25,185
Non-PCI Loans | Noncommercial | Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	[1]			(10,018)
Unpaid principal balance		1,294	1,067
ALLL for loans and leases individually evaluated for impairment		527	555
Impaired Financing Receivable, with Related Allowance, Recorded Investment		1,050	987
Impaired Financing Receivable, with No Related Allowance, Recorded Investment		188	8
Financing Receivable, Individually Evaluated for Impairment		1,238	995
Average balance		1,126	1,535	1,427
Interest income recognized		75	88	53
Allowance for loan and lease losses		19,496	16,555	13,541		25,389
Non-PCI Loans | Noncommercial | Non-specific
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	[1]			(15,772)
Allowance for loan and lease losses		0	0	0		15,850
PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Reclassification	[1]			0
Acquired loans which have adverse change in expected cash flows		469,252	285,636
Allowance for loan and lease losses		16,312	21,629	53,520		139,972
PCI Loans | Commercial | Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses		773	75	1,354		11,234
PCI Loans | Commercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses		1,082	150	1,320		31,186
PCI Loans | Commercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses		7,838	10,135	29,906		50,275
PCI Loans | Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses		445	1,240	5,275		8,897
PCI Loans | Noncommercial | Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses		0	183	682		8,287
PCI Loans | Noncommercial | Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses		5,398	5,820	11,802		19,837
PCI Loans | Noncommercial | Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan and lease losses		$ 523	$ 3,999	$ 2,959		$ 9,754

[1] Reclassification results from enhancements to the ALLL calculation during the second quarter of 2013 that resulted in the allocation of $15.8 million previously designated as 'nonspecific' to other loan classes and the absorption of $7.4 million of the reserve for unfunded commitments related to unfunded, revocable loan commitments into the ALLL. Further discussion is contained in Note A.