Loans - Changes in Accretable Yield for Covered Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance, beginning of period	$ 415,179	$ 336,208
Acquisition	0	126,930
Accretion	(107,482)	(105,078)
Net (decrease) increase in expected cash flows	(9,989)	57,119
Other, net	(3,194)	0
Balance, end of period	$ 294,514	$ 415,179