Loans and Leases - Summary of Changes in Accretable Yield for Acquired Loans (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Purchased Impaired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	$ 184,618	$ 76,518	$ 37,230
Additions		117,251
Interest income	(52,769)	(28,551)	(21,263)
Reclassifications from nonaccretable balance	22,384	19,400	60,551
Balance at end of period	154,233	184,618	76,518
Other Acquired [Member]
Summary of changes in Accretable Yield for acquired loans
Balance at beginning of period	296,434	397,379	538,633
Interest income	(123,044)	(158,260)	(178,670)
Reclassifications from nonaccretable balance	22,677	49,930	24,907
Other	5,086	7,385	12,509
Balance at end of period	$ 201,153	$ 296,434	$ 397,379