Debt and Financing Arrangements - Summary of Recognized Interest Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Total interest expense	$ 1,777	$ 1,760	$ 4,986	$ 5,019
Credit Facility [Member]
Debt Instrument [Line Items]
Total interest expense	$ 1,777	$ 1,760	$ 4,986	5,011
2006 Convertible Senior Subordinated Notes [Member]
Debt Instrument [Line Items]
Total interest expense				$ 8