Long-Term Debt (Credit Facility) - Additional Information (Detail) - Revolving Credit Facility [Member]	9 Months Ended
	Sep. 30, 2015 USD ($)
Debt Instrument [Line Items]
Amended date of line of credit	Apr. 20, 2015
Expiration date of line of credit	Aug. 01, 2018
Line of credit facility, extension term	1 year
Line of credit facility, maximum borrowing capacity	$ 125,000,000
Long-term debt LIBOR plus interest rate, reckoning period	30 days
Line of credit facility unused portion of borrowing capacity description	The Credit Facility also accrues a fee of 20 to 25 basis points for any unused portion of the borrowing capacity based on whether the unused portion is greater or less than 50% of the total borrowing capacity.
Line of credit facility unused portion of the borrowing capacity fee percentage condition	50.00%
Line of credit facility, maturity date	Aug. 01, 2018
Line of credit facility, current borrowing capacity	$ 75,000,000
Amended Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity	$ 48,800,000
Minimum [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate description	LIBOR plus 135 basis
Line of credit facility, basis points added to LIBOR interest rate	1.35%
Line of credit facility, commitment fee percentage on unused portion of the borrowing capacity	0.20%
Maximum [Member]
Debt Instrument [Line Items]
Line of credit facility, interest rate description	LIBOR plus 225 basis
Line of credit facility, basis points added to LIBOR interest rate	2.25%
Line of credit facility, commitment fee percentage on unused portion of the borrowing capacity	0.25%