Loans - Changes in Accretable Yield for Covered Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance, beginning of period	$ 387,120	$ 309,858	$ 415,179	$ 336,208
Accretion	(31,519)	(27,757)	(59,578)	(54,107)
Balance, end of period	$ 355,601	$ 282,101	$ 355,601	$ 282,101