Fair Value (Details 8) (Level 3, USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Excess Servicing Spread
Quantitative summary of key inputs used in the valuation and the effect on estimated fair value from adverse changes in those assumptions
Pricing spread (as a percent)	6.80%
Average life (in years)	6 years 8 months 12 days
Prepayment speed (as a percent)	9.10%
Purchased MSRs backed by distressed mortgage loans | Period end | Fair value
Quantitative summary of key inputs used in the valuation and the effect on estimated fair value from adverse changes in those assumptions
Carrying value	$ 10,125	$ 12,370
Unpaid principal balance of underlying loans	1,051,220	1,271,478
Weighted-average note rate (as a percent)	5.88%	6.01%
Weighted-average servicing fee rate (as a percent)	0.50%	0.50%
Effect on value of 5% adverse change	(252)	(302)
Effect on value of 10% adverse change	(494)	(590)
Effect on value of 20% adverse change	(945)	(1,130)
Effect on value of 5% adverse change	(252)	(273)
Effect on value of 10% adverse change	(492)	(529)
Effect on value of 20% adverse change	(951)	(1,040)
Effect on value of 5% adverse change	(223)	(290)
Effect on value of 10% adverse change	(447)	(580)
Effect on value of 20% adverse change	(893)	(1,159)
Purchased MSRs backed by distressed mortgage loans | Period end | Fair value | Minimum
Quantitative summary of key inputs used in the valuation and the effect on estimated fair value from adverse changes in those assumptions
Discount rate (as a percent)	15.30%	15.30%
Average life (in years)	4 years 9 months 18 days	5 years
Prepayment speed (as a percent)	11.70%	10.70%
Annual per-loan cost of servicing	250	270
Purchased MSRs backed by distressed mortgage loans | Period end | Fair value | Maximum
Quantitative summary of key inputs used in the valuation and the effect on estimated fair value from adverse changes in those assumptions
Discount rate (as a percent)	15.30%	15.30%
Average life (in years)	4 years 9 months 18 days	5 years
Prepayment speed (as a percent)	11.70%	10.70%
Annual per-loan cost of servicing	250	270
Purchased MSRs backed by distressed mortgage loans | Period end | Fair value | Weighted average
Quantitative summary of key inputs used in the valuation and the effect on estimated fair value from adverse changes in those assumptions
Discount rate (as a percent)	15.30%	15.30%
Average life (in years)	4 years 9 months 18 days	5 years
Prepayment speed (as a percent)	11.70%	10.70%
Annual per-loan cost of servicing	250	270
All other MSRs | Period end | Fair value
Quantitative summary of key inputs used in the valuation and the effect on estimated fair value from adverse changes in those assumptions
Carrying value	16,643	7,428
Unpaid principal balance of underlying loans	1,700,612	1,166,765
Weighted-average note rate (as a percent)	4.68%	5.22%
Weighted-average servicing fee rate (as a percent)	0.27%	0.26%
Effect on value of 5% adverse change	(303)	(113)
Effect on value of 10% adverse change	(596)	(222)
Effect on value of 20% adverse change	(1,153)	(430)
Effect on value of 5% adverse change	(376)	(238)
Effect on value of 10% adverse change	(738)	(462)
Effect on value of 20% adverse change	(1,423)	(877)
Effect on value of 5% adverse change	(150)	(77)
Effect on value of 10% adverse change	(300)	(153)
Effect on value of 20% adverse change	(601)	(307)
All other MSRs | Period end | Fair value | Minimum
Quantitative summary of key inputs used in the valuation and the effect on estimated fair value from adverse changes in those assumptions
Pricing spread (as a percent)	6.40%	7.50%
Average life (in years)	2 months 12 days	2 months 12 days
Prepayment speed (as a percent)	8.70%	9.00%
Annual per-loan cost of servicing	68	68
All other MSRs | Period end | Fair value | Maximum
Quantitative summary of key inputs used in the valuation and the effect on estimated fair value from adverse changes in those assumptions
Pricing spread (as a percent)	17.50%	19.50%
Average life (in years)	14 years 4 months 24 days	14 years 4 months 24 days
Prepayment speed (as a percent)	72.80%	84.20%
Annual per-loan cost of servicing	120	140
All other MSRs | Period end | Fair value | Weighted average
Quantitative summary of key inputs used in the valuation and the effect on estimated fair value from adverse changes in those assumptions
Pricing spread (as a percent)	8.90%	10.60%
Average life (in years)	6 years 7 months 6 days	5 years
Prepayment speed (as a percent)	10.60%	19.20%
Annual per-loan cost of servicing	77	76
All other MSRs | Period end | Amortized cost
Quantitative summary of key inputs used in the valuation and the effect on estimated fair value from adverse changes in those assumptions
Carrying value	226,090	89,177
Unpaid principal balance of underlying loans	20,024,781	8,730,686
Weighted-average note rate (as a percent)	3.57%	3.65%
Weighted-average servicing fee rate (as a percent)	0.28%	0.28%
Effect on value of 5% adverse change	(4,833)	(1,814)
Effect on value of 10% adverse change	(9,488)	(3,562)
Effect on value of 20% adverse change	(18,303)	(6,870)
Effect on value of 5% adverse change	(4,696)	(1,751)
Effect on value of 10% adverse change	(9,238)	(3,446)
Effect on value of 20% adverse change	(17,891)	(6,674)
Effect on value of 5% adverse change	(2,383)	(963)
Effect on value of 10% adverse change	(4,766)	(1,926)
Effect on value of 20% adverse change	(9,531)	(3,852)
All other MSRs | Period end | Amortized cost | Minimum
Quantitative summary of key inputs used in the valuation and the effect on estimated fair value from adverse changes in those assumptions
Pricing spread (as a percent)	5.40%	7.50%
Average life (in years)	2 years 7 months 6 days	2 years 6 months
Prepayment speed (as a percent)	8.50%	8.70%
Annual per-loan cost of servicing	68	68
All other MSRs | Period end | Amortized cost | Maximum
Quantitative summary of key inputs used in the valuation and the effect on estimated fair value from adverse changes in those assumptions
Pricing spread (as a percent)	15.90%	16.50%
Average life (in years)	6 years 10 months 24 days	6 years 10 months 24 days
Prepayment speed (as a percent)	16.00%	28.30%
Annual per-loan cost of servicing	120	140
All other MSRs | Period end | Amortized cost | Weighted average
Quantitative summary of key inputs used in the valuation and the effect on estimated fair value from adverse changes in those assumptions
Pricing spread (as a percent)	7.60%	9.80%
Average life (in years)	6 years 8 months 12 days	6 years 7 months 6 days
Prepayment speed (as a percent)	9.00%	9.20%
Annual per-loan cost of servicing	$ 102	$ 99