Loans Receivable and Allowance for Loan Losses (Details 4) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
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	$ 346,906	$ 301,535
Loans collectively evaluated for impairment	12,809,008	12,896,025
Total loans	13,155,914	13,197,560
Loans individually evaluated for impairment, allowance for loan losses	5,046	15,148
Loans collectively evaluated for impairment, allowance for loan losses	140,455	142,037
Total allowance for loan losses	145,501	157,185	201,499	194,049
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 collectively evaluated for impairment	264,094	282,444
Total loans	264,094	282,444
Loans collectively evaluated for impairment, allowance for loan losses	6,316	3,800
Total allowance for loan losses	6,316	3,800	4,146	6,978
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 loans	12,891,820	12,915,116
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	272,146	245,671
Loans collectively evaluated for impairment	9,439,080	10,315,868
Total loans	9,711,226	10,561,539
Loans individually evaluated for impairment, allowance for loan losses	1,001	3,305
Loans collectively evaluated for impairment, allowance for loan losses	88,266	102,686
Total allowance for loan losses	89,267	105,991	125,524	113,288
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	56,116	38,769
Loans collectively evaluated for impairment	2,350,562	1,655,102
Total loans	2,406,678	1,693,871
Loans individually evaluated for impairment, allowance for loan losses	2,576	8,650
Loans collectively evaluated for impairment, allowance for loan losses	32,938	26,772
Total allowance for loan losses	35,514	35,422	56,266	63,145
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	18,644	17,095
Loans collectively evaluated for impairment	755,272	642,611
Total loans	773,916	659,706
Loans individually evaluated for impairment, allowance for loan losses	1,469	3,193
Loans collectively evaluated for impairment, allowance for loan losses	12,935	8,779
Total allowance for loan losses	$ 14,404	$ 11,972	$ 15,563	$ 10,638