Loans and the Allowance for Loan Losses (Details 9) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	$ 482,080		$ 248,029
Impaired Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	25,319		31,904
Other Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	170,693		205,184
Not Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	286,068		10,941
Contractually Required Principal And Interest [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	653,787
Contractually Required Principal And Interest [Member] | Impaired Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	67,522
Contractually Required Principal And Interest [Member] | Other Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	214,907
Contractually Required Principal And Interest [Member] | Not Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	371,358
Nonaccretable Difference [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	(131,957)	[1]
Nonaccretable Difference [Member] | Impaired Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	(42,202)	[1]
Nonaccretable Difference [Member] | Other Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	(40,896)	[1]
Nonaccretable Difference [Member] | Not Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	(48,859)	[1]
Cash Flows Expected to be Collected [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	521,830
Cash Flows Expected to be Collected [Member] | Impaired Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	25,320
Cash Flows Expected to be Collected [Member] | Other Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	174,011
Cash Flows Expected to be Collected [Member] | Not Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	322,499
Accretable Yield [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	(39,750)	[2]
Accretable Yield [Member] | Impaired Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	(1)	[2]
Accretable Yield [Member] | Other Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	(3,318)	[2]
Accretable Yield [Member] | Not Covered Loans [Member]
Fair value of loans determined to be impaired and not to be impaired at the time of acquisition
Loans acquired with deteriorated credit quality	$ (36,431)	[2]

[1] Represents contractual principal and interest cash flows of $641,495 and $12,292, respectively, not expected to be collected.

[2] Represents contractual interest payments of $3,355 expected to be collected and purchase discount of $36,395.