Loans - Changes in Accretable Yield for Covered Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance, beginning of period	$ 309,858	$ 209,865	$ 336,208	$ 223,799
Accretion	(27,757)	(17,509)	(54,107)	(31,443)
Net decrease in expected cash flows	0	(70,014)	0	(70,014)
Balance, end of period	$ 282,101	$ 122,342	$ 282,101	$ 122,342