Fair Value Measurement - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instruments transferred into or out of Level 3 classification	$ 0	$ 0	$ 0
Level 3 instruments recorded	0	0	0
Meridian [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Selling and administrative expense			$ 231,000