Loans, Leases and Allowance for Credit Losses - Tabular Disclosure of Nonperforming Assets (Detail) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment, Nonaccrual Status	[1]	$ 40,272	$ 48,381
Loans past due 90 days or more on accrual status		1,067	3,028
Troubled debt restructured loans	[2]	53,637	70,707
Total nonperforming loans		94,976	122,116
Other assets acquired through foreclosure, net		47,815	43,942	$ 57,150	$ 66,719
Total nonperforming assets		142,791	166,058
Troubled Debt Restructured Loans [Member]
Financing Receivable, Recorded Investment, Nonaccrual Status		$ 7,100	$ 18,200

[1] Includes non-accrual TDR loans of $7.1 million and $18.2 million at December 31, 2016 and 2015, respectively.

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