Loans Receivable and Allowance for Loan Losses (Allowance for Loan Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	$ 107,500	$ 118,600	$ 111,600	$ 139,000
Provision (credited) charged to operations	(4,439)	(3,042)	(7,749)	(7,153)
Charge-offs	(1,615)	(4,904)	(5,896)	(27,370)
Recoveries	2,054	2,946	5,545	9,123
Balance at the end of the period	103,500	113,600	103,500	113,600
Consumer and Other Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	8,770	9,540	8,825	8,824
Provision (credited) charged to operations	202	147	363	2,097
Charge-offs	(80)	(352)	(515)	(1,776)
Recoveries	82	91	301	281
Balance at the end of the period	8,974	9,426	8,974	9,426
Mortgage loans (gross) | Residential
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	44,546	56,552	46,283	80,337
Provision (credited) charged to operations	(1,992)	(7,617)	(2,346)	(20,225)
Charge-offs	(982)	(2,134)	(4,341)	(19,061)
Recoveries	669	2,531	2,645	8,281
Balance at the end of the period	42,241	49,332	42,241	49,332
Mortgage loans (gross) | Multi-family
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	38,794	37,075	39,250	36,703
Provision (credited) charged to operations	409	3,183	(998)	4,457
Charge-offs	(553)	(2,275)	(898)	(3,414)
Recoveries	216	324	1,512	561
Balance at the end of the period	38,866	38,307	38,866	38,307
Mortgage loans (gross) | Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	15,390	15,433	17,242	13,136
Provision (credited) charged to operations	(3,058)	1,245	(4,768)	6,518
Charge-offs	0	(143)	(142)	(3,119)
Recoveries	1,087	0	1,087	0
Balance at the end of the period	$ 13,419	$ 16,535	$ 13,419	$ 16,535