Loans Receivable and Allowance for Loan Losses - Changes in Allowance for Loan Losses by Loan Receivable Segment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Allowance for Loan and Lease Losses
Balance at the beginning of the period	$ 86,100	$ 98,000
Provision charged (credited) to operations	(2,486)	(3,127)
Charge-offs	(2,381)	(2,740)
Recoveries	1,267	2,067
Balance at the end of the period	82,500	94,200
Consumer and Other Loans
Allowance for Loan and Lease Losses
Balance at the beginning of the period	5,461	6,288
Provision charged (credited) to operations	(125)	841
Charge-offs	(112)	(765)
Recoveries	71	70
Balance at the end of the period	5,295	6,434
Mortgage Loans | Residential
Allowance for Loan and Lease Losses
Balance at the beginning of the period	36,439	44,951
Provision charged (credited) to operations	(901)	138
Charge-offs	(2,235)	(1,665)
Recoveries	1,048	954
Balance at the end of the period	34,351	44,378
Mortgage Loans | Multi-Family
Allowance for Loan and Lease Losses
Balance at the beginning of the period	34,901	35,544
Provision charged (credited) to operations	(957)	(3,257)
Charge-offs	(34)	(310)
Recoveries	39	1,043
Balance at the end of the period	33,949	33,020
Mortgage Loans | Commercial Real Estate
Allowance for Loan and Lease Losses
Balance at the beginning of the period	9,299	11,217
Provision charged (credited) to operations	(503)	(849)
Charge-offs	0	0
Recoveries	109	0
Balance at the end of the period	$ 8,905	$ 10,368