Deposits (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Weighted Average Rate:
Savings (as a percent)	0.05%	0.25%
Money market (as a percent)	0.74%	0.71%
NOW (as a percent)	0.05%	0.10%
Total core deposits (as a percent)	0.21%	0.28%
Certificates of deposit (as a percent)	1.55%	1.93%
Total deposits (as a percent)	0.72%	1.09%
Balance:
Savings	$ 2,802,298	$ 2,750,715
Money market	1,586,556	1,114,404
NOW	1,259,771	1,117,173
Non-interest bearing NOW and demand deposit	834,962	744,315
Total core deposits	6,483,587	5,726,607
Certificates of deposit	3,960,371	5,519,007
Total deposits	$ 10,443,958	$ 11,245,614
Percent of Total:
Savings (as a percent)	26.83%	24.46%
Money market (as a percent)	15.19%	9.91%
NOW (as a percent)	12.06%	9.93%
Non-interest bearing NOW and demand deposit (as a percent)	8.00%	6.62%
Total core deposits (as a percent)	62.08%	50.92%
Certificates of deposit (as a percent)	37.92%	49.08%
Total deposits (as a percent)	100.00%	100.00%