Loans Receivable and Allowance for Loan Losses (Schedule of Allowance for Loan Losses by Portfolio Segment) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	$ 61,734	$ 64,664
Provision charged to operations	600	400
Recoveries of loans previously charged-off	491	431
Loans charged-off	(1,715)	(2,075)
Balance at end of period	61,110	63,420
Mortgage Loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	31,977	34,144
Provision charged to operations	1,038	(2,000)
Recoveries of loans previously charged-off	65	67
Loans charged-off	(194)	(741)
Balance at end of period	32,886	31,470
Commercial Loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	24,381	24,107
Provision charged to operations	(477)	1,330
Recoveries of loans previously charged-off	215	243
Loans charged-off	(422)	(519)
Balance at end of period	23,697	25,161
Consumer Loans [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	4,881	4,929
Provision charged to operations	284	144
Recoveries of loans previously charged-off	211	121
Loans charged-off	(1,099)	(815)
Balance at end of period	4,277	4,379
Total Portfolio Segments [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	61,239	63,180
Provision charged to operations	845	(526)
Recoveries of loans previously charged-off	491	431
Loans charged-off	(1,715)	(2,075)
Balance at end of period	60,860	61,010
Unallocated [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Balance at beginning of period	495	1,484
Provision charged to operations	(245)	926
Recoveries of loans previously charged-off	0	0
Loans charged-off	0	0
Balance at end of period	$ 250	$ 2,410