Investment Securities - Gross Unrealized Losses and Fair Value, Aggregated by Investment Category (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, fair value	$ 334,656	$ 60,388
Less than 12 months, unrealized losses	(7,863)	(81)
12 months or more, fair value	57,363	80,431
12 months or more, unrealized losses	(2,207)	(2,268)
Fair value, total	392,019	140,819
Unrealized losses, total	(10,070)	(2,349)
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, fair value	305,702	60,388
Less than 12 months, unrealized losses	(4,384)	(81)
12 months or more, fair value	57,357	80,426
12 months or more, unrealized losses	(2,206)	(2,267)
Fair value, total	363,059	140,814
Unrealized losses, total	(6,590)	(2,348)
Corporate notes
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, fair value	9,748
Less than 12 months, unrealized losses	(178)
12 months or more, fair value	0
12 months or more, unrealized losses	0
Fair value, total	9,748
Unrealized losses, total	(178)
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Less than 12 months, fair value	19,206	0
Less than 12 months, unrealized losses	(3,301)	0
12 months or more, fair value	6	5
12 months or more, unrealized losses	(1)	(1)
Fair value, total	19,212	5
Unrealized losses, total	$ (3,302)	$ (1)