Loans and the Allowance for Loan Losses - (Details 9) - Receivables Acquired with Deteriorated Credit Quality - USD ($) $ in Thousands		Jun. 30, 2015	Dec. 31, 2014	Sep. 01, 2013
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality		$ 292,100	$ 344,425	$ 899,236
Impaired Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality		15,358	8,004
Other Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality		106,268	135,037
Not Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality		170,474	$ 201,384
Contractually-required principal and interest
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality		402,871
Contractually-required principal and interest | Impaired Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality		35,544
Contractually-required principal and interest | Other Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality		122,104
Contractually-required principal and interest | Not Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality		245,223
Nonaccretable difference
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality	[1]	(87,461)
Nonaccretable difference | Impaired Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality	[1]	(20,180)
Nonaccretable difference | Other Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality	[1]	(15,139)
Nonaccretable difference | Not Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality	[1]	(52,142)
Cash flows expected to be collected
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality		315,410
Cash flows expected to be collected | Impaired Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality		15,364
Cash flows expected to be collected | Other Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality		106,965
Cash flows expected to be collected | Not Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality		193,081
Accretable yield
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality	[2]	(23,310)
Accretable yield | Impaired Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality	[2]	(6)
Accretable yield | Other Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality	[2]	(697)
Accretable yield | Not Covered Loans
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality	[2]	$ (22,607)
Contractually-required principal and interest
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality				1,112,979
Cash flows expected to be collected
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality				1,042,645
Nonaccretable difference
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality				70,334
Accretable yield
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Acquired with deteriorated credit quality				$ 143,409

[1] Represents contractual principal and interest cash flows of $82,546 and $4,915, respectively, not expected to be collected.

[2] Represents contractual interest payments of $788 expected to be collected and purchase discount of $22,522.