Loans Receivable and Allowance for Loan Losses (Residential Mortgage, Consumer and Other Loans, by Class and Credit Quality Indicator) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Financing Receivable, Recorded Investment
Total	$ 10,800,918	$ 11,111,727
Consumer and Other Loans
Financing Receivable, Recorded Investment
Total	257,429	252,693
Consumer and Other Loans | Home Equity and Other Consumer
Financing Receivable, Recorded Investment
Total	149,380	160,819
Consumer and Other Loans | Commercial and Industrial
Financing Receivable, Recorded Investment
Total	108,049	91,874
Mortgage Loans
Financing Receivable, Recorded Investment
Total	10,543,489	10,859,034
Mortgage Loans | Residential Mortgage Loans
Financing Receivable, Recorded Investment
Total	5,633,421	6,015,415
Mortgage Loans | Residential Mortgage Loans | Full Documentation Interest-Only
Financing Receivable, Recorded Investment
Total	337,170	432,288
Mortgage Loans | Residential Mortgage Loans | Full Documentation Amortizing
Financing Receivable, Recorded Investment
Total	4,488,373	4,697,966
Mortgage Loans | Residential Mortgage Loans | Reduced Documentation Interest-Only
Financing Receivable, Recorded Investment
Total	182,264	303,231
Mortgage Loans | Residential Mortgage Loans | Reduced Documentation Amortizing
Financing Receivable, Recorded Investment
Total	625,614	581,930
Performing | Consumer and Other Loans | Home Equity and Other Consumer
Financing Receivable, Recorded Investment
Total	143,825	154,414
Performing | Consumer and Other Loans | Commercial and Industrial
Financing Receivable, Recorded Investment
Total	107,558	91,171
Performing | Mortgage Loans | Residential Mortgage Loans | Full Documentation Interest-Only
Financing Receivable, Recorded Investment
Total	319,406	413,913
Performing | Mortgage Loans | Residential Mortgage Loans | Full Documentation Amortizing
Financing Receivable, Recorded Investment
Total	4,434,321	4,653,437
Performing | Mortgage Loans | Residential Mortgage Loans | Reduced Documentation Interest-Only
Financing Receivable, Recorded Investment
Total	162,843	275,659
Performing | Mortgage Loans | Residential Mortgage Loans | Reduced Documentation Amortizing
Financing Receivable, Recorded Investment
Total	579,344	552,070
Non-performing | Consumer and Other Loans | Home Equity and Other Consumer | Current or past due less than 90 days
Financing Receivable, Recorded Investment
Total	271	0
Non-performing | Consumer and Other Loans | Home Equity and Other Consumer | Past due 90 days or more
Financing Receivable, Recorded Investment
Total	5,284	6,405
Non-performing | Consumer and Other Loans | Commercial and Industrial | Current or past due less than 90 days
Financing Receivable, Recorded Investment
Total	0	0
Non-performing | Consumer and Other Loans | Commercial and Industrial | Past due 90 days or more
Financing Receivable, Recorded Investment
Total	491	703
Non-performing | Mortgage Loans | Residential Mortgage Loans | Full Documentation Interest-Only | Current or past due less than 90 days
Financing Receivable, Recorded Investment
Total	4,812	7,016
Non-performing | Mortgage Loans | Residential Mortgage Loans | Full Documentation Interest-Only | Past due 90 days or more
Financing Receivable, Recorded Investment
Total	12,952	11,359
Non-performing | Mortgage Loans | Residential Mortgage Loans | Full Documentation Amortizing | Current or past due less than 90 days
Financing Receivable, Recorded Investment
Total	13,017	11,662
Non-performing | Mortgage Loans | Residential Mortgage Loans | Full Documentation Amortizing | Past due 90 days or more
Financing Receivable, Recorded Investment
Total	41,035	32,867
Non-performing | Mortgage Loans | Residential Mortgage Loans | Reduced Documentation Interest-Only | Current or past due less than 90 days
Financing Receivable, Recorded Investment
Total	6,441	12,287
Non-performing | Mortgage Loans | Residential Mortgage Loans | Reduced Documentation Interest-Only | Past due 90 days or more
Financing Receivable, Recorded Investment
Total	12,980	15,285
Non-performing | Mortgage Loans | Residential Mortgage Loans | Reduced Documentation Amortizing | Current or past due less than 90 days
Financing Receivable, Recorded Investment
Total	17,138	15,538
Non-performing | Mortgage Loans | Residential Mortgage Loans | Reduced Documentation Amortizing | Past due 90 days or more
Financing Receivable, Recorded Investment
Total	$ 29,132	$ 14,322