Loss Reserves - Narrative (Details) $ in Millions		1 Months Ended	12 Months Ended
	Dec. 01, 2012 USD ($) Installment	Dec. 31, 2012 USD ($)	Dec. 31, 2015 USD ($) loan	Dec. 31, 2014 USD ($) loan	Dec. 31, 2013 loan
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Premium refund liability, expected claim payments			$ 102.0	$ 115.0
Pool insurance notice inventory (in number of loans) | loan			2,739	3,797	6,563
Percent of inventory in default for more than 36 consecutive months			50.00%	53.00%	49.00%
Number of rescindable loans affected by Company's decision to voluntarily suspend rescissions | loan			435
Premium refund liability, expected future rescissions			$ 7.0	$ 28.0
Freddie Mac's Disagreement on Aggregate Loss Limit
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Obligations under the disputed policies	$ 267.5
Amount paid as per settlement agreement		$ 100.0
Remaining amount of unpaid settlement agreement		$ 167.5
Number of installments to pay settlement agreement amount | Installment	48
(Decrease) Increase in Estimated Claim Rate on primary Defaults
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Percentage of prior year default inventory resolved (in hundredths)			60.00%	58.00%	59.00%