Fair Value Accounting - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Financing Receivable, Recorded Investment		$ 113,706	$ 99,209
Aggregate carrying amount of impaired loans	[1]	10,919	10,909
Impaired loans with an allowance recorded		(3,965)	(4,239)
Other assets acquired through foreclosure		45,200	47,800
Goodwill		$ 289,895	$ 289,967
Common Stock, Shares, Issued		106,929,801	106,371,093
Collateralized debt obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities contained credit losses		0
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans with an allowance recorded		$ (4,000)	$ (4,200)
Junior Subordinated Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Junior subordinated debt, Input Value		5.54%	5.66%
Period of basis point spread		4.39%	4.66%
Percentage of LIBOR		1.14956%	1.00%
Fair Value, Measurements, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate carrying amount of impaired loans		$ 6,954	$ 6,670
Other assets acquired through foreclosure		45,200	47,815
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired Financing Receivable, Recorded Investment		86,305	67,408
Aggregate carrying amount of impaired loans		6,954	6,670
Other assets acquired through foreclosure		$ 45,200	$ 47,815

[1] Includes TDR loans of $7.1 million and $2.5 million at March 31, 2017 and December 31, 2016, respectively.