Loans Receivable and Allowance for Loan Losses - Summary of Loans Receivable by Portfolio Segment and Impairment Method (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	$ 93,839	$ 106,370
Collectively evaluated for impairment	5,813,848	5,090,293
Total loans	5,907,687	5,196,663
Mortgage Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	67,110	75,839
Collectively evaluated for impairment	4,021,324	3,611,023
Total loans	4,088,434	3,686,862
Commercial Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	24,458	28,210
Collectively evaluated for impairment	1,177,283	903,989
Total loans	1,201,741	932,199
Consumer Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Individually evaluated for impairment	2,271	2,321
Collectively evaluated for impairment	615,241	575,281
Total loans	$ 617,512	$ 577,602