Loans and Leases - Summary of Changes in Accretable Yield for Acquired Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Purchased Impaired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	$ 76,518	$ 37,230	$ 42,252
Additions	117,251
Interest income	(28,551)	(21,263)	(36,727)
Reclassifications from nonaccretable balance, net	19,400	60,551	31,705
Balance at end of period	184,618	76,518	37,230
Other Acquired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	397,379	538,633	638,272
Interest income	(158,260)	(178,670)	(247,295)
Reclassifications from nonaccretable balance, net	49,930	24,907	149,595
Other	7,385	12,509	(1,939)
Balance at end of period	$ 296,434	$ 397,379	$ 538,633