Subsequent Event - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		1 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Business Segment	Sep. 30, 2012 Business Segment	Sep. 30, 2013 Business Segment	Sep. 30, 2012 Business Segment	Sep. 30, 2013 Pro Forma Net revenue excluding GVE	Sep. 30, 2012 Pro Forma Net revenue excluding GVE	Sep. 30, 2013 Pro Forma Net revenue excluding GVE	Sep. 30, 2012 Pro Forma Net revenue excluding GVE	Sep. 30, 2013 Pro Forma Business Segment	Sep. 30, 2012 Pro Forma Business Segment	Sep. 30, 2013 Pro Forma Business Segment	Sep. 30, 2012 Pro Forma Business Segment	Oct. 21, 2013 GVE Newco, LLC Subsequent Event	Oct. 21, 2013 GVE Newco, LLC Subsequent Event Class A Common Stock
Subsequent Event [Line Items]
Total consideration received for sale of subsidiary																	$ 51,500,000
Cash received sale of subsidiary																	47,500,000
Amount of shares received for divestiture																	666,978
Common stock value																		1,000,000
Accounts receivable																	2,000,000
Accrued payable																	1,000,000
Net revenue	$ 52,798,000	$ 42,983,000	$ 153,975,000	$ 135,762,000	$ 35,814,000	$ 27,059,000	$ 102,365,000	$ 81,347,000	$ 40,200,000	$ 34,200,000	$ 120,700,000	$ 107,700,000	$ 23,200,000	$ 18,200,000	$ 69,100,000	$ 53,300,000