Covered Assets and Indemnification Asset - Internal Risk Grades (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Internal risk grades of covered loans in the portfolio
Total loans	$ 5,783,853	$ 5,843,499
Covered
Internal risk grades of covered loans in the portfolio
Total loans	235,434	256,127
Covered | PCI loans
Internal risk grades of covered loans in the portfolio
Total loans	118,393	133,754
Covered | Pass
Internal risk grades of covered loans in the portfolio
Total loans	106,591	111,432
Covered | Special Mention
Internal risk grades of covered loans in the portfolio
Total loans	453	461
Covered | Substandard
Internal risk grades of covered loans in the portfolio
Total loans	9,997	10,480
Covered | Secured
Internal risk grades of covered loans in the portfolio
Total loans	1,849	2,398
Covered | Secured | PCI loans
Internal risk grades of covered loans in the portfolio
Total loans	728	1,213
Covered | Secured | Pass
Internal risk grades of covered loans in the portfolio
Total loans	543	592
Covered | Secured | Substandard
Internal risk grades of covered loans in the portfolio
Total loans	578	593
Covered | Unsecured
Internal risk grades of covered loans in the portfolio
Total loans	173	299
Covered | Unsecured | PCI loans
Internal risk grades of covered loans in the portfolio
Total loans	173	299
Covered | Secured by Commercial Properties
Internal risk grades of covered loans in the portfolio
Total loans	63,201	72,094
Covered | Secured by Commercial Properties | PCI loans
Internal risk grades of covered loans in the portfolio
Total loans	44,681	52,637
Covered | Secured by Commercial Properties | Pass
Internal risk grades of covered loans in the portfolio
Total loans	17,210	17,996
Covered | Secured by Commercial Properties | Substandard
Internal risk grades of covered loans in the portfolio
Total loans	1,310	1,461
Covered | Secured by Residential Properties
Internal risk grades of covered loans in the portfolio
Total loans	164,040	172,375
Covered | Secured by Residential Properties | PCI loans
Internal risk grades of covered loans in the portfolio
Total loans	70,235	74,401
Covered | Secured by Residential Properties | Pass
Internal risk grades of covered loans in the portfolio
Total loans	86,695	90,563
Covered | Secured by Residential Properties | Special Mention
Internal risk grades of covered loans in the portfolio
Total loans	453	461
Covered | Secured by Residential Properties | Substandard
Internal risk grades of covered loans in the portfolio
Total loans	6,657	6,950
Covered | Commercial construction loans and land development
Internal risk grades of covered loans in the portfolio
Total loans	6,171	8,961
Covered | Commercial construction loans and land development | PCI loans
Internal risk grades of covered loans in the portfolio
Total loans	2,576	5,204
Covered | Commercial construction loans and land development | Pass
Internal risk grades of covered loans in the portfolio
Total loans	2,143	2,281
Covered | Commercial construction loans and land development | Substandard
Internal risk grades of covered loans in the portfolio
Total loans	$ 1,452	$ 1,476