Covered Loans - Schedule of Acquired Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Impaired Loans By Type [Line Items]
Beginning balance	$ 77,053	$ 131,038
Principal reductions and interest payments	(10,268)	(25,574)
Accretion of loan discount	3,344	11,339
Changes in contractual and expected cash flows due to remeasurement	65	1,534
Removals due to foreclosure or sale	(429)	(3,837)
Ending balance	69,765	114,500
Contractual Cash Flows [Member]
Impaired Loans By Type [Line Items]
Beginning balance	124,809	251,042
Principal reductions and interest payments	(9,566)	(25,353)
Changes in contractual and expected cash flows due to remeasurement	(498)	(3,159)
Removals due to foreclosure or sale	(433)	(3,133)
Ending balance	114,312	219,397
Non Accretable Difference [Member]
Impaired Loans By Type [Line Items]
Beginning balance	(12,014)	(46,793)
Principal reductions and interest payments	(702)	(221)
Changes in contractual and expected cash flows due to remeasurement	3,695	18,105
Removals due to foreclosure or sale	133	1,302
Ending balance	(8,888)	(27,607)
Accretable Yield [Member]
Impaired Loans By Type [Line Items]
Beginning balance	(35,742)	(73,211)
Accretion of loan discount	3,344	11,339
Changes in contractual and expected cash flows due to remeasurement	(3,132)	(13,412)
Removals due to foreclosure or sale	(129)	(2,006)
Ending balance	$ (35,659)	$ (77,290)

Accretion of loan discount on covered loans that were acquired with deteriorated credit quality.

No definition available.

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Changes in contractual and expected cash flows due to remeasurement on covered loans that were acquired with deteriorated credit quality.

No definition available.

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Principal reductions and interest payments on covered loans that were acquired with deteriorated credit quality.

No definition available.

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Removals due to foreclosure or sale of covered loans that were acquired with deteriorated credit quality.

No definition available.

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The carrying amount, net of allowance for loan losses of covered loans that were acquired with deteriorated credit quality.

No definition available.

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