Fair Value Measurements - Significant Unobservable Inputs in Fair Value Measurement Level 3 Assets and Liabilities (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned, fair value	$ 29,290	$ 39,340
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, fair value	6,031,880	5,207,971
Fair Value, Measurements, Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned, fair value	29,290	$ 39,340
Fair Value, Measurements, Nonrecurring | Level 3 | Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans, fair value	6,031,880
Fair Value, Measurements, Nonrecurring | Level 3 | Other real estate owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other real estate owned, fair value	$ 29,290
Range	10.00%
Fair Value, Measurements, Nonrecurring | Level 3 | Minimum | Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range	0.00%
Fair Value, Measurements, Nonrecurring | Level 3 | Maximum | Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range	100.00%