Loans Receivable and Allowance for Loan Losses (Schedule of Allowance for Loan Losses by Portfolio Segment) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 61,424	$ 61,734
Provision charged to operations	1,500	600
Recoveries of loans previously charged-off	579	491
Loans charged-off	(1,312)	(1,715)
Balance at end of period	62,191	61,110
Mortgage Loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	32,094	31,977
Provision charged to operations	(1,193)	1,038
Recoveries of loans previously charged-off	172	65
Loans charged-off	(224)	(194)
Balance at end of period	30,849	32,886
Commercial Loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	25,829	24,381
Provision charged to operations	2,958	(477)
Recoveries of loans previously charged-off	91	215
Loans charged-off	(623)	(422)
Balance at end of period	28,255	23,697
Consumer Loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	3,501	4,881
Provision charged to operations	(265)	284
Recoveries of loans previously charged-off	316	211
Loans charged-off	(465)	(1,099)
Balance at end of period	3,087	4,277
Total Portfolio Segments [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	61,424	61,239
Provision charged to operations	1,500	845
Recoveries of loans previously charged-off	579	491
Loans charged-off	(1,312)	(1,715)
Balance at end of period	62,191	60,860
Unallocated [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	0	495
Provision charged to operations	0	(245)
Recoveries of loans previously charged-off	0	0
Loans charged-off	0	0
Balance at end of period	$ 0	$ 250