Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Rent expense for office lease	$ 0.1	$ 0.1	$ 0.2	$ 0.2
Percentage of limited company liability subsidiaries	100.00%		100.00%
Aggregate purchase price	106.5		106.5
Purchase Agreement paid	0.5		0.5
Deferred loan acquisition costs	$ 0.3		$ 0.3