Debt - Additional Information (Detail) (USD $)	1 Months Ended	12 Months Ended		0 Months Ended
	Oct. 31, 2010	Dec. 31, 2013	Dec. 31, 2012	Jan. 07, 2014 Promissory Note [Member] Subsequent Event [Member]
Debt Instrument [Line Items]
Line of credit facility drawn		$ 22,000,000	$ 19,500,000
Letter of credit outstanding		6,700,000	6,000,000
Line of credit facility interest rate		4.25%
Percentage of credit fee on unused amount		0.50%
Credit fees on the Credit Facility		979,000	1,000,000
Excess amount of stock repurchase	50,000,000	50,000,000
Promissory note Aggregate principal amount				1,200,000
Promissory note maturity date				Jan. 06, 2019
Promissory note principal payment				$ 23,000
Promissory note interest rate percentage				4.50%