Loans Receivable and Allowance for Loan Losses - Changes in Allowance for Loan Losses by Loan Receivable Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	$ 111,600	$ 139,000	$ 145,501
Provision charged (credited) to operations	(12,072)	(9,469)	19,601
Charge-offs	(8,270)	(29,589)	(37,040)
Recoveries	6,742	11,658	10,938
Balance at the end of the period	98,000	111,600	139,000
Consumer and Other Loans
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	8,825	8,824	6,316
Provision charged (credited) to operations	(2,002)	1,709	3,604
Charge-offs	(912)	(2,073)	(1,916)
Recoveries	377	365	820
Balance at the end of the period	6,288	8,825	8,824
Mortgage Loans | Residential
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	46,283	80,337	89,267
Provision charged (credited) to operations	1,520	(23,464)	9,368
Charge-offs	(6,149)	(19,868)	(26,644)
Recoveries	3,297	9,278	8,346
Balance at the end of the period	44,951	46,283	80,337
Mortgage Loans | Multi- Family
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	39,250	36,703	35,514
Provision charged (credited) to operations	(4,780)	5,337	4,684
Charge-offs	(907)	(4,365)	(4,732)
Recoveries	1,981	1,575	1,237
Balance at the end of the period	35,544	39,250	36,703
Mortgage Loans | Commercial Real Estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance at the beginning of the period	17,242	13,136	14,404
Provision charged (credited) to operations	(6,810)	6,949	1,945
Charge-offs	(302)	(3,283)	(3,748)
Recoveries	1,087	440	535
Balance at the end of the period	$ 11,217	$ 17,242	$ 13,136