Special Charges - Additional Information (Detail) - USD ($)	3 Months Ended			12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Other Income And Expenses [Abstract]
Special charges	$ 1,628,000	$ 5,347,000	$ 9,364,000	$ 0	$ 16,339,000	$ 38,414,000
Non cash special charges					700,000	14,100,000
Total cash outflow associated with special charges, amount paid					$ 65,500,000	$ 65,500,000	$ 65,500,000
Cash outflow associated with special charges, amount paid				53,700,000
Cash outflow associated with special charges, amount expected to be paid in 2016				3,200,000
Cash outflow associated with special charges, amount expected to be paid in 2017				3,200,000
Cash outflow associated with special charges, amount expected to be paid in 2018				2,600,000
Cash outflow associated with special charges, amount expected to be paid in 2019				1,200,000
Cash outflow associated with special charges, amount expected to be paid from 2020 to 2025				$ 1,600,000