Loans Receivable and Allowance for Loan Losses (Allowance for Loan Losses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	$ 94,200	$ 110,500	$ 98,000	$ 111,600
Provision (credited) charged to operations	(3,006)	(2,967)	(6,133)	(3,310)
Charge-offs	(2,083)	(1,791)	(4,823)	(4,281)
Recoveries	889	1,758	2,956	3,491
Balance at the end of the period	90,000	107,500	90,000	107,500
Consumer and Other Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	6,434	9,819	6,288	8,825
Provision (credited) charged to operations	518	(1,073)	1,359	161
Charge-offs	(95)	(86)	(860)	(435)
Recoveries	83	110	153	219
Balance at the end of the period	6,940	8,770	6,940	8,770
Mortgage Loans | Residential
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	44,378	43,481	44,951	46,283
Provision (credited) charged to operations	(1,658)	1,497	(1,520)	(354)
Charge-offs	(1,826)	(1,602)	(3,491)	(3,359)
Recoveries	326	1,170	1,280	1,976
Balance at the end of the period	41,220	44,546	41,220	44,546
Mortgage Loans | Multi-Family
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	33,020	40,082	35,544	39,250
Provision (credited) charged to operations	(1,270)	(1,663)	(4,527)	(1,407)
Charge-offs	(99)	(103)	(409)	(345)
Recoveries	480	478	1,523	1,296
Balance at the end of the period	32,131	38,794	32,131	38,794
Mortgage Loans | Commercial Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	10,368	17,118	11,217	17,242
Provision (credited) charged to operations	(596)	(1,728)	(1,445)	(1,710)
Charge-offs	(63)	0	(63)	(142)
Recoveries	0	0	0	0
Balance at the end of the period	$ 9,709	$ 15,390	$ 9,709	$ 15,390