Loans and the Allowance for Loan Losses (Details 9) (USD $) In Thousands, unless otherwise specified	Jun. 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	$ 212,081		$ 248,029
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	289,006
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	(72,015)	[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	216,991
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	(4,910)	[2]
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	25,370		31,904
Impaired Covered Loans [Member] | 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	66,879
Impaired Covered Loans [Member] | 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	(41,507)	[1]
Impaired Covered Loans [Member] | 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	25,372
Impaired Covered Loans [Member] | 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	(2)	[2]
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	176,124		205,184
Other Covered Loans [Member] | 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	209,442
Other Covered Loans [Member] | 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	(29,413)	[1]
Other Covered Loans [Member] | 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	180,029
Other Covered Loans [Member] | 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	(3,905)	[2]
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	10,587		10,941
Not Covered Loans [Member] | 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	12,685
Not Covered Loans [Member] | 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	(1,095)	[1]
Not Covered Loans [Member] | 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	11,590
Not Covered Loans [Member] | 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	$ (1,003)	[2]

[1] Represents contractual principal and interest cash flows of $276,704 and $12,302, respectively, not expected to be collected.

[2] Represents contractual interest payments of $3,980 expected to be collected and purchase discount of $930.