Loans - Changes in Accretable Yield for Covered Loans (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Mar. 31, 2014	Mar. 31, 2013
Receivables [Abstract]
Balance, beginning of period			$ 223,799	$ 169,309	$ 122,342	$ 256,383
Accretion	(15,538)	(16,990)	(46,981)	(50,864)
Net increase in expected cash flows	0	0	(70,014)	120,948
Balance, end of period	$ 106,804	$ 239,393	$ 106,804	$ 239,393	$ 122,342	$ 256,383