Loans Receivable and Allowance for Loan Losses (Loans Receivable and Related Allowance by Impairment Methodology) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2012
Balances of our loans receivable and the related allowance for loan loss allocation by segment and by the impairment methodology followed in determining the allowance for loan losses
Loans individually evaluated for impairment	$ 250,749		$ 384,522
Loans collectively evaluated for impairment	11,616,015		12,001,856
Total	11,866,764		12,386,378
Loans individually evaluated for impairment, allowance for loan losses	19,885		21,531
Loans collectively evaluated for impairment, allowance for loan losses	93,715		117,469
Total allowance for loan losses	113,600	118,600	139,000	143,000	143,900	145,501
Consumer and Other Loans
Balances of our loans receivable and the related allowance for loan loss allocation by segment and by the impairment methodology followed in determining the allowance for loan losses
Loans individually evaluated for impairment	5,768
Loans collectively evaluated for impairment	239,228		239,681
Total	244,996		239,681
Loans individually evaluated for impairment, allowance for loan losses	4,340
Loans collectively evaluated for impairment, allowance for loan losses	5,086		8,824
Total allowance for loan losses	9,426	9,540	8,824	7,327	7,605	6,316
Mortgage loans (gross)
Balances of our loans receivable and the related allowance for loan loss allocation by segment and by the impairment methodology followed in determining the allowance for loan losses
Total	11,621,768		12,146,697
Mortgage loans (gross) | Residential
Balances of our loans receivable and the related allowance for loan loss allocation by segment and by the impairment methodology followed in determining the allowance for loan losses
Loans individually evaluated for impairment	181,486		311,930
Loans collectively evaluated for impairment	6,900,738		7,725,346
Total	7,082,224		8,037,276
Loans individually evaluated for impairment, allowance for loan losses	9,789		18,352
Loans collectively evaluated for impairment, allowance for loan losses	39,543		61,985
Total allowance for loan losses	49,332	56,552	80,337	83,424	78,788	89,267
Mortgage loans (gross) | Multi-family
Balances of our loans receivable and the related allowance for loan loss allocation by segment and by the impairment methodology followed in determining the allowance for loan losses
Loans individually evaluated for impairment	44,312		52,538
Loans collectively evaluated for impairment	3,614,924		3,243,917
Total	3,659,236		3,296,455
Loans individually evaluated for impairment, allowance for loan losses	3,448		2,877
Loans collectively evaluated for impairment, allowance for loan losses	34,859		33,826
Total allowance for loan losses	38,307	37,075	36,703	38,245	40,865	35,514
Mortgage loans (gross) | Commercial real estate
Balances of our loans receivable and the related allowance for loan loss allocation by segment and by the impairment methodology followed in determining the allowance for loan losses
Loans individually evaluated for impairment	19,183		20,054
Loans collectively evaluated for impairment	861,125		792,912
Total	880,308		812,966
Loans individually evaluated for impairment, allowance for loan losses	2,308		302
Loans collectively evaluated for impairment, allowance for loan losses	14,227		12,834
Total allowance for loan losses	$ 16,535	$ 15,433	$ 13,136	$ 14,004	$ 16,642	$ 14,404