Covered Assets and Indemnification Asset - Internal Risk Grades (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Internal risk grades of covered loans in the portfolio
Total	$ 5,366,065	$ 5,220,040
Covered
Internal risk grades of covered loans in the portfolio
Total	347,386	380,294
Covered | PCI loans
Internal risk grades of covered loans in the portfolio
Total	197,865	221,974
Covered | Pass
Internal risk grades of covered loans in the portfolio
Total	134,606	143,067
Covered | Special Mention
Internal risk grades of covered loans in the portfolio
Total	484	491
Covered | Substandard
Internal risk grades of covered loans in the portfolio
Total	14,431	14,762
Covered | Secured
Internal risk grades of covered loans in the portfolio
Total	7,280	7,021
Covered | Secured | PCI loans
Internal risk grades of covered loans in the portfolio
Total	5,163	5,727
Covered | Secured | Pass
Internal risk grades of covered loans in the portfolio
Total	1,118	758
Covered | Secured | Substandard
Internal risk grades of covered loans in the portfolio
Total	999	536
Covered | Unsecured
Internal risk grades of covered loans in the portfolio
Total	1,790	1,780
Covered | Unsecured | PCI loans
Internal risk grades of covered loans in the portfolio
Total	1,790	1,780
Covered | Secured by commercial properties
Internal risk grades of covered loans in the portfolio
Total	115,174	125,985
Covered | Secured by commercial properties | PCI loans
Internal risk grades of covered loans in the portfolio
Total	88,077	96,928
Covered | Secured by commercial properties | Pass
Internal risk grades of covered loans in the portfolio
Total	22,565	24,070
Covered | Secured by commercial properties | Substandard
Internal risk grades of covered loans in the portfolio
Total	4,532	4,987
Covered | Secured by residential properties
Internal risk grades of covered loans in the portfolio
Total	203,747	215,063
Covered | Secured by residential properties | PCI loans
Internal risk grades of covered loans in the portfolio
Total	88,864	96,618
Covered | Secured by residential properties | Pass
Internal risk grades of covered loans in the portfolio
Total	107,719	111,128
Covered | Secured by residential properties | Special Mention
Internal risk grades of covered loans in the portfolio
Total	484	491
Covered | Secured by residential properties | Substandard
Internal risk grades of covered loans in the portfolio
Total	6,680	6,826
Covered | Residential construction loans
Internal risk grades of covered loans in the portfolio
Total	685	925
Covered | Residential construction loans | PCI loans
Internal risk grades of covered loans in the portfolio
Total	165	121
Covered | Residential construction loans | Pass
Internal risk grades of covered loans in the portfolio
Total		264
Covered | Residential construction loans | Substandard
Internal risk grades of covered loans in the portfolio
Total	520	540
Covered | Commercial construction loans and land development
Internal risk grades of covered loans in the portfolio
Total	18,710	29,520
Covered | Commercial construction loans and land development | PCI loans
Internal risk grades of covered loans in the portfolio
Total	13,806	20,800
Covered | Commercial construction loans and land development | Pass
Internal risk grades of covered loans in the portfolio
Total	3,204	6,847
Covered | Commercial construction loans and land development | Substandard
Internal risk grades of covered loans in the portfolio
Total	$ 1,700	$ 1,873