Commitments and Contingencies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified		1 Months Ended			9 Months Ended
	Sep. 30, 2013	Feb. 28, 2010 Faigin Matter	Aug. 31, 2007 Colburn Matter	Jun. 30, 2011 Walker Matter	Sep. 30, 2013 Breach Of Employment Contracts LegalMatter
Commitments And Contingencies Disclosure [Line Items]
Court awarded amount to plaintiff		$ 1.4
Damages sought by Signature	4.6
Total amount claimed by plaintiff			2.6	2.5
Plaintiff superior court claim			3.2	4.6
Bankruptcy claims filed in court					$ 5.1
Number of Bankruptcy claims filed					2