Non-Covered Loans and Allowance for Non-Covered Loan Losses (Details 5) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Total loans	$ 4,834,687	$ 3,920,476
Noncovered
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Total loans	4,834,687	3,920,476
Noncovered | PCI loans
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Total loans	114,868	48,909
Noncovered | Consumer
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Total loans	52,408	53,147
Noncovered | Consumer | PCI loans
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Total loans	1,549	2,138
Noncovered | Bank
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans past Due 30-59 Days	18,025	11,537
Loans past Due 60-89 Days	7,382	2,191
Loans past Due 90 Days or More	10,049	8,597
Total Past Due Loans	35,456	22,325
Current Loans	4,684,363	3,849,242
Total loans	4,834,687	3,920,476
Noncovered | Bank | PCI loans
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Total loans	114,868	48,909
Noncovered | Bank | Secured
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans past Due 30-59 Days	2,451	6,073
Loans past Due 60-89 Days	7,216	964
Loans past Due 90 Days or More	9,449	8,022
Total Past Due Loans	19,116	15,059
Current Loans	2,073,061	1,620,000
Total loans	2,112,080	1,648,433
Noncovered | Bank | Secured | PCI loans
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Total loans	19,903	13,374
Noncovered | Bank | Unsecured
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans past Due 30-59 Days	285	35
Loans past Due 60-89 Days		3
Total Past Due Loans	285	38
Current Loans	109,362	110,312
Total loans	109,647	110,418
Noncovered | Bank | Unsecured | PCI loans
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Total loans		68
Noncovered | Bank | Secured by commercial properties
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans past Due 30-59 Days	346	67
Total Past Due Loans	346	67
Current Loans	1,306,125	1,173,504
Total loans	1,369,298	1,195,912
Noncovered | Bank | Secured by commercial properties | PCI loans
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Total loans	62,827	22,341
Noncovered | Bank | Secured by residential properties
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans past Due 30-59 Days	955	454
Loans past Due 60-89 Days	147	1,187
Total Past Due Loans	1,102	1,641
Current Loans	676,031	495,472
Total loans	697,961	498,923
Noncovered | Bank | Secured by residential properties | PCI loans
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Total loans	20,828	1,810
Noncovered | Bank | Residential construction loans
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans past Due 30-59 Days	297	175
Total Past Due Loans	297	175
Current Loans	74,601	64,871
Total loans	75,131	65,046
Noncovered | Bank | Residential construction loans | PCI loans
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Total loans	233
Noncovered | Bank | Commercial construction loans and land development
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans past Due 30-59 Days	13,335	4,319
Loans past Due 90 Days or More	600	575
Total Past Due Loans	13,935	4,894
Current Loans	394,699	334,525
Total loans	418,162	348,597
Noncovered | Bank | Commercial construction loans and land development | PCI loans
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Total loans	9,528	9,178
Noncovered | Bank | Consumer
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Loans past Due 30-59 Days	356	414
Loans past Due 60-89 Days	19	37
Total Past Due Loans	375	451
Current Loans	50,484	50,558
Total loans	52,408	53,147
Noncovered | Bank | Consumer | PCI loans
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Total loans	1,549	2,138
Noncovered | Prime Lending | U.S. government agencies
Non-Covered Loans and Allowance for Non-Covered Loan Losses
Accruing Loans Past Due 90 Days or More	$ 24,200	$ 19,200