Loans Receivable and Allowance for Loan Losses - Balances of Loan Receivable and Related Allowance for Loan Loss Allocation (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Loans:
Individually evaluated for impairment	$ 237,518	$ 248,436
Collectively evaluated for impairment	10,874,209	11,661,286
Total	11,111,727	11,909,722
Allowance for loan losses:
Individually evaluated for impairment	14,813	19,732
Collectively evaluated for impairment	83,187	91,868
Total allowance for loan losses	98,000	111,600	$ 139,000	$ 145,501
Consumer and Other Loans
Loans:
Individually evaluated for impairment	4,968	5,153
Collectively evaluated for impairment	247,725	244,215
Total	252,693	249,368
Allowance for loan losses:
Individually evaluated for impairment	421	3,810
Collectively evaluated for impairment	5,867	5,015
Total allowance for loan losses	6,288	8,825	8,824	6,316
Mortgage Loans
Loans:
Total	10,859,034	11,660,354
Mortgage Loans \| Residential
Loans:
Individually evaluated for impairment	192,914	181,402
Collectively evaluated for impairment	5,822,501	6,692,134
Total	6,015,415	6,873,536
Allowance for loan losses:
Individually evaluated for impairment	13,148	10,304
Collectively evaluated for impairment	31,803	35,979
Total allowance for loan losses	44,951	46,283	80,337	89,267
Mortgage Loans \| Multi-family
Loans:
Individually evaluated for impairment	24,643	42,611
Collectively evaluated for impairment	3,999,462	3,870,442
Total	4,024,105	3,913,053
Allowance for loan losses:
Individually evaluated for impairment	456	3,172
Collectively evaluated for impairment	35,088	36,078
Total allowance for loan losses	35,544	39,250	36,703	35,514
Mortgage Loans \| Commercial real estate
Loans:
Individually evaluated for impairment	14,993	19,270
Collectively evaluated for impairment	804,521	854,495
Total	819,514	873,765
Allowance for loan losses:
Individually evaluated for impairment	788	2,446
Collectively evaluated for impairment	10,429	14,796
Total allowance for loan losses	$ 11,217	$ 17,242	$ 13,136	$ 14,404

Financing Receivable, Allowance for Credit Losses, Evaluated for Impairment [Abstract]

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Financing Receivable, Evaluated for Impairment [Abstract]

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No definition available.

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Reflects the aggregate gross carrying amount of all categories of loans held in portfolio, prior to deducting deferred income and the allowance for losses on loans.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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The balance of financing receivables that were collectively evaluated for impairment.

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The balance of financing receivables that were individually evaluated for impairment.

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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-Section 50
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 6
-Section L
-Subsection 1

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