Unaudited Quarterly Financial Data (Details) (USD $)	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013		Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Unaudited Quarterly Financial Data [Abstract]
Net premiums written	$ 204,081,000		$ 234,278,000		$ 236,622,000		$ 248,500,000		$ 260,736,000	[1]	$ 263,505,000		$ 238,605,000		$ 254,986,000		$ 923,481,000		$ 1,017,832,000		$ 1,064,380,000
Net premiums earned	226,358,000		231,857,000		237,777,000		247,059,000		261,705,000	[1]	266,432,000		242,628,000		262,405,000		943,051,000		1,033,170,000		1,123,835,000
Investment income, net of expenses	21,278,000		20,250,000		20,883,000		18,328,000		21,660,000	[1]	30,394,000		32,178,000		37,408,000		80,739,000		121,640,000		201,270,000
Loss incurred, net	196,055,000		180,189,000		196,274,000		266,208,000		688,636,000	[1]	490,121,000		551,408,000		337,088,000		838,726,000		2,067,253,000		1,714,707,000
Change in premium deficiency reserve (note 10)	(8,574,000)		(3,813,000)		(11,283,000)		(1,650,000)		(10,351,000)	[1]	(9,144,000)		(27,358,000)		(14,183,000)		(25,320,000)		(61,036,000)		(44,150,000)
Underwriting and other operating expenses	46,974,000		47,970,000		47,562,000		50,012,000		51,516,000	[1]	50,678,000		48,910,000		50,343,000		192,518,000		201,447,000
Interest expense	17,662,000		17,653,000		17,942,000		26,406,000		25,327,000	[1]	24,478,000		24,912,000		24,627,000		79,663,000		99,344,000		103,271,000
Net income (loss)	(1,407,000)		12,114,000		12,375,000		(72,930,000)		(386,691,000)	[1]	(246,942,000)		(273,891,000)		(19,555,000)		(49,848,000)		(927,079,000)		(485,892,000)
Income (loss) per share [Abstract]
Basic (in dollars per share)	$ 0	[2]	$ 0.04	[2]	$ 0.04	[2]	$ (0.31)	[2]	$ (1.91)	[1],[2]	$ (1.22)	[2]	$ (1.36)	[2]	$ (0.10)	[2]	$ (0.16)	[2]	$ (4.59)	[2]	$ (2.42)
Diluted (in dollars per share)	$ 0	[2]	$ 0.04	[2]	$ 0.04	[2]	$ (0.31)	[2]	$ (1.91)	[1],[2]	$ (1.22)	[2]	$ (1.36)	[2]	$ (0.10)	[2]	$ (0.16)	[2]	$ (4.59)	[2]	$ (2.42)
Obligations under the disputed policies																			267,000,000
Increase in loss reserves for the probable settlement agreements																			$ 100,000,000

[1] The results for the fourth quarter of 2012 include a loss of approximately $267 million related to our settlement with Freddie Mac and approximately $100 million related to our probable rescission settlement agreements. See Note 20 – “Litigation and Contingencies.”

[2] Due to the use of weighted average shares outstanding when calculating earnings per share, the sum of the quarterly per share data may not equal the per share data for the year.