Covered Assets and Indemnification Asset (Details 6) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Internal risk grades of covered loans in the portfolio
Total	$ 4,834,687	$ 3,920,476
Covered
Internal risk grades of covered loans in the portfolio
Total	552,014	642,640
Covered | PCI loans
Internal risk grades of covered loans in the portfolio
Total	360,095	435,388
Covered | Pass
Internal risk grades of covered loans in the portfolio
Total	173,928	188,420
Covered | Substandard
Internal risk grades of covered loans in the portfolio
Total	17,991	18,832
Covered | Secured
Internal risk grades of covered loans in the portfolio
Total	16,742	22,765
Covered | Secured | PCI loans
Internal risk grades of covered loans in the portfolio
Total	11,683	13,630
Covered | Secured | Pass
Internal risk grades of covered loans in the portfolio
Total	3,500	7,712
Covered | Secured | Substandard
Internal risk grades of covered loans in the portfolio
Total	1,559	1,423
Covered | Unsecured
Internal risk grades of covered loans in the portfolio
Total	5,607	8,015
Covered | Unsecured | PCI loans
Internal risk grades of covered loans in the portfolio
Total	4,897	6,805
Covered | Unsecured | Pass
Internal risk grades of covered loans in the portfolio
Total	702	1,210
Covered | Unsecured | Substandard
Internal risk grades of covered loans in the portfolio
Total	8
Covered | Secured by commercial properties
Internal risk grades of covered loans in the portfolio
Total	216,447	270,329
Covered | Secured by commercial properties | PCI loans
Internal risk grades of covered loans in the portfolio
Total	178,288	227,772
Covered | Secured by commercial properties | Pass
Internal risk grades of covered loans in the portfolio
Total	32,228	35,973
Covered | Secured by commercial properties | Substandard
Internal risk grades of covered loans in the portfolio
Total	5,931	6,584
Covered | Secured by residential properties
Internal risk grades of covered loans in the portfolio
Total	261,593	282,521
Covered | Secured by residential properties | PCI loans
Internal risk grades of covered loans in the portfolio
Total	125,886	141,192
Covered | Secured by residential properties | Pass
Internal risk grades of covered loans in the portfolio
Total	128,453	133,756
Covered | Secured by residential properties | Substandard
Internal risk grades of covered loans in the portfolio
Total	7,254	7,573
Covered | Residential construction loans
Internal risk grades of covered loans in the portfolio
Total	1,567	1,640
Covered | Residential construction loans | PCI loans
Internal risk grades of covered loans in the portfolio
Total	287	354
Covered | Residential construction loans | Pass
Internal risk grades of covered loans in the portfolio
Total	267	268
Covered | Residential construction loans | Substandard
Internal risk grades of covered loans in the portfolio
Total	1,013	1,018
Covered | Commercial construction loans and land development
Internal risk grades of covered loans in the portfolio
Total	50,058	57,370
Covered | Commercial construction loans and land development | PCI loans
Internal risk grades of covered loans in the portfolio
Total	39,054	45,635
Covered | Commercial construction loans and land development | Pass
Internal risk grades of covered loans in the portfolio
Total	8,778	9,501
Covered | Commercial construction loans and land development | Substandard
Internal risk grades of covered loans in the portfolio
Total	$ 2,226	$ 2,234