Loans Receivable and Allowance for Loan Losses (Summary of Allowance for Loan Losses by Portfolio Segment and Impairment Classification) (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	$ 2,127		$ 2,271
Collectively evaluated for impairment	58,961		59,153
Total	61,088	$ 60,933	61,424	$ 60,464	$ 59,624	$ 61,734
Mortgage Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	1,963		2,086
Collectively evaluated for impairment	27,691		30,008
Total	29,654	31,634	32,094	31,622	31,824	31,977
Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	81		91
Collectively evaluated for impairment	28,158		25,738
Total	28,239	26,299	25,829	25,076	22,840	24,381
Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	83		94
Collectively evaluated for impairment	3,112		3,407
Total	$ 3,195	$ 3,000	$ 3,501	$ 3,739	$ 4,570	$ 4,881