Loans - Changes in Accretable Yield for Covered Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance, beginning of period	$ 355,601	$ 282,101	$ 415,179	$ 336,208
Accretion	(26,730)	(24,814)	(86,308)	(78,921)
Balance, end of period	$ 328,871	$ 257,287	$ 328,871	$ 257,287