Loans Receivable and Allowance for Loan Losses (Details 5) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Recorded Investment
Total	$ 11,909,722	$ 12,386,378
Past due 90 days or more	62,834	250,534
Consumer and other loans
Recorded Investment
Total	249,368	239,681
Past due 90 days or more	6,040	5,948
Consumer and other loans | Home equity and other consumer
Recorded Investment
Total	184,553	208,923
Consumer and other loans | Commercial and industrial
Recorded Investment
Total	64,815	30,758
Mortgage loans (gross)
Recorded Investment
Total	11,660,354	12,146,697
Past due 90 days or more	56,794	244,586
Mortgage loans (gross) | Residential mortgage loans
Recorded Investment
Total	6,873,536	8,037,276
Past due 90 days or more	44,989	234,378
Mortgage loans (gross) | Residential mortgage loans | Full documentation interest-only loans
Recorded Investment
Total	854,182	1,382,201
Past due 90 days or more	11,502	78,271
Mortgage loans (gross) | Residential mortgage loans | Full documentation amortizing loans
Recorded Investment
Total	5,003,693	5,419,457
Past due 90 days or more	14,355	42,085
Mortgage loans (gross) | Residential mortgage loans | Reduced documentation interest-only loans
Recorded Investment
Total	611,008	839,661
Past due 90 days or more	16,289	87,910
Mortgage loans (gross) | Residential mortgage loans | Reduced documentation amortizing loans
Recorded Investment
Total	404,653	395,957
Past due 90 days or more	2,843	26,112
Performing | Consumer and other loans | Home equity and other consumer
Recorded Investment
Total	178,513	202,943
Performing | Consumer and other loans | Commercial and industrial
Recorded Investment
Total	64,815	30,758
Performing | Mortgage loans (gross) | Residential mortgage loans | Full documentation interest-only loans
Recorded Investment
Total	826,155	1,281,973
Performing | Mortgage loans (gross) | Residential mortgage loans | Full documentation amortizing loans
Recorded Investment
Total	4,981,880	5,364,548
Performing | Mortgage loans (gross) | Residential mortgage loans | Reduced documentation interest-only loans
Recorded Investment
Total	568,424	721,503
Performing | Mortgage loans (gross) | Residential mortgage loans | Reduced documentation amortizing loans
Recorded Investment
Total	396,922	363,626
Non-performing | Consumer and other loans | Home equity and other consumer
Recorded Investment
Current or past due less than 90 days		32
Past due 90 days or more	6,040	5,948
Non-performing | Mortgage loans (gross) | Residential mortgage loans | Full documentation interest-only loans
Recorded Investment
Current or past due less than 90 days	16,525	21,957
Past due 90 days or more	11,502	78,271
Non-performing | Mortgage loans (gross) | Residential mortgage loans | Full documentation amortizing loans
Recorded Investment
Current or past due less than 90 days	7,458	12,824
Past due 90 days or more	14,355	42,085
Non-performing | Mortgage loans (gross) | Residential mortgage loans | Reduced documentation interest-only loans
Recorded Investment
Current or past due less than 90 days	26,295	30,248
Past due 90 days or more	16,289	87,910
Non-performing | Mortgage loans (gross) | Residential mortgage loans | Reduced documentation amortizing loans
Recorded Investment
Current or past due less than 90 days	4,888	6,219
Past due 90 days or more	$ 2,843	$ 26,112