Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012 Employment Matter	Sep. 30, 2012 Employment Matter Other Current Liabilities	Sep. 30, 2012 Employment Matter Other Current Assets	Apr. 30, 2012 License Fees	Jul. 31, 2012 Subscription Agreements	Jan. 13, 2012 Intellectual Property Rights
Commitments and Contingencies
Contractual commitment							$ 0.8
Contractual commitment due in current year					0.8		0.2
Contractual commitment due in two years					0.8	0.6	0.2
Contractual commitment due in three years					0.8	0.8	0.2
Contractual commitment due in four years						1.0	0.2
Operating lease commitments due in current year	0.2
Operating lease commitments due in two years	0.5
Increase in capital lease commitments through 2015	1.6
Estimated range of probable loss, minimum		1.6
Estimated range of probable loss, maximum		2.0
Estimated range of probable loss, amount accrued			1.6
Insurance receivable				1.6
Estimated possible loss, amount not accrued		$ 0.4