Loans and Leases - Certain Information Relating to Commercial Real Estate Loans (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016
Loans and Leases Receivable Disclosure [Line Items]
Commercial construction loans	$ 1,050,129	$ 459,995
Credit Concentration Risk [Member] | Commercial Construction Loans [Member]
Loans and Leases Receivable Disclosure [Line Items]
Percent of total loans and leases	5.20%	3.10%
Loan Portfolio Diversification Risk [Member] | Commercial Real Estate Loans [Member] | Owner-Occupied [Member]
Loans and Leases Receivable Disclosure [Line Items]
Percent of total loans and leases	37.40%	36.20%
Loan Portfolio Diversification Risk [Member] | Commercial Real Estate Loans [Member] | Non-Owner-Occupied [Member]
Loans and Leases Receivable Disclosure [Line Items]
Percent of total loans and leases	62.60%	63.80%