Loans Receivable and Allowance for Loan Losses - Summary of Loans Receivable by Portfolio Segment and Impairment Method (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	$ 94,626	$ 106,370
Collectively evaluated for impairment	5,165,053	5,090,293
Total loans	5,259,679	5,196,663
Mortgage Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	67,374	75,839
Collectively evaluated for impairment	3,653,725	3,611,023
Total loans	3,721,099	3,686,862
Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	24,958	28,210
Collectively evaluated for impairment	941,486	903,989
Total loans	966,444	932,199
Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	2,294	2,321
Collectively evaluated for impairment	569,842	575,281
Total loans	$ 572,136	$ 577,602