Financial Instruments - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Assets Sold Under Agreements To Repurchase [Line Items]
Long-term debt, fair value	$ 516,500,000		$ 516,500,000		$ 513,500,000
Long-term debt, carrying value	500,000,000		500,000,000		$ 500,000,000
Gain/Loss on remeasurement of contingent consideration	$ 0	$ 1,700,000	$ 1,000,000	$ 1,700,000
Contractual Settlement		$ 1,500,000		$ 1,500,000
6.0% Senior Notes Due 2022
Assets Sold Under Agreements To Repurchase [Line Items]
Interest percentage	6.00%		6.00%
Debt maturity period			2022		2022
Senior Bank Credit Facility
Assets Sold Under Agreements To Repurchase [Line Items]
Line of credit maximum borrowing capacity	$ 550,000,000		$ 550,000,000		$ 550,000,000