Income Tax - Additional Information (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Income Tax Examination [Line Items]
Deferred tax asset, gross	$ 10,600,000	$ 13,500,000
Deferred tax liability, gross	27,900,000	31,700,000
Total available gross net operating loss	7,900,000
Future realized windfall tax benefit	6,300,000
Open tax uncertainty positions	0
Windfall [Member]
Income Tax Examination [Line Items]
Total available gross net operating loss	$ 47,000,000