Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 State and Local Jurisdiction [Member]	Sep. 30, 2013 Foreign Tax Authority [Member]	Jul. 02, 2013 Knight [Member]
Income Tax Contingency [Line Items]
Deferred tax asset							$ 65,900,000
Deferred tax benefit resulting from the Company becoming subject to U.S. corporate income taxes	103,499,000	0	103,499,000	0
Operating loss carryforwards	89,200,000		89,200,000			68,700,000
Deferred tax assets, operating loss carryforwards	31,200,000		31,200,000
Deferred tax assets, valuation allowance	6,800,000		6,800,000
Deferred income tax asset						17,900,000
Foreign tax credit carryforwards						3,200,000
State and local offsetting valuation allowance						1,600,000
General business carry forward	2,500,000		2,500,000
AMT Carryforward					6,800,000
Unrecognized tax benefits that would impact effective tax rate if recognized	$ 1,400,000		$ 1,400,000