Investment Securities - Schedule of Investment Securities' Gross Unrealized Losses and Fair Value by Investment Category (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less than 12 months, Fair Value	$ 17,650	$ 430,729
Available-for-sale securities, Less than 12 months, Unrealized Loss	67	4,710
Available-for-sale securities, 12 months or longer, Fair Value	5,383	32,938
Available-for-sale securities, 12 months or longer, Unrealized Loss	17	952
Available-for-sale securities, Total, Fair Value	23,033	463,667
Available-for-sale securities, Total, Unrealized Loss	84	5,662
Held-to-maturity, Less than 12 months, Fair Value		9,845
Held-to-maturity, Less than 12 months, Unrealized Loss		62
Held-to-maturity, 12 months or longer, Fair Value	2,449
Held-to-maturity, 12 months or longer, Unrealized Loss	20
Held-to-maturity, Total, Fair Value	2,449	9,845
Held-to-maturity, Total, Unrealized Loss	20	62
CMO [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less than 12 months, Fair Value	4,992	139,486
Available-for-sale securities, Less than 12 months, Unrealized Loss	15	1,703
Available-for-sale securities, 12 months or longer, Fair Value	5,383	26,536
Available-for-sale securities, 12 months or longer, Unrealized Loss	17	711
Available-for-sale securities, Total, Fair Value	10,375	166,022
Available-for-sale securities, Total, Unrealized Loss	32	2,414
FNMA MBS [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less than 12 months, Fair Value	4,119	214,465
Available-for-sale securities, Less than 12 months, Unrealized Loss	23	2,715
Available-for-sale securities, Total, Fair Value	4,119	214,465
Available-for-sale securities, Total, Unrealized Loss	23	2,715
FHLMC MBS [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less than 12 months, Fair Value		41,791
Available-for-sale securities, Less than 12 months, Unrealized Loss		136
Available-for-sale securities, 12 months or longer, Fair Value		4,025
Available-for-sale securities, 12 months or longer, Unrealized Loss		177
Available-for-sale securities, Total, Fair Value		45,816
Available-for-sale securities, Total, Unrealized Loss		313
GNMA MBS [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less than 12 months, Fair Value	8,539	4,073
Available-for-sale securities, Less than 12 months, Unrealized Loss	29	29
Available-for-sale securities, 12 months or longer, Fair Value		2,377
Available-for-sale securities, 12 months or longer, Unrealized Loss		64
Available-for-sale securities, Total, Fair Value	8,539	6,450
Available-for-sale securities, Total, Unrealized Loss	29	93
GSE [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, Less than 12 months, Fair Value		30,914
Available-for-sale securities, Less than 12 months, Unrealized Loss		127
Available-for-sale securities, Total, Fair Value		30,914
Available-for-sale securities, Total, Unrealized Loss		127
State and Political Subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Held-to-maturity, Less than 12 months, Fair Value		9,845
Held-to-maturity, Less than 12 months, Unrealized Loss		62
Held-to-maturity, 12 months or longer, Fair Value	2,449
Held-to-maturity, 12 months or longer, Unrealized Loss	20
Held-to-maturity, Total, Fair Value	2,449	9,845
Held-to-maturity, Total, Unrealized Loss	$ 20	$ 62

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
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