Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Equity [Abstract]
Balance at beginning of period, Pension and Postretirement Benefit Plans	$ 71,625	$ 29,287	$ 68,568	$ 29,198
Other comprehensive earnings, tax effect, Pension and Postretirement Benefit Plans	(1,042)	(96)	2,015	(7)
Balance at end of period, Pension and Postretirement Benefit Plans	70,583	29,191	70,583	29,191
Balance at beginning of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	1,554	2,039	1,799	2,269
Other comprehensive earnings, tax effect, Unamortized Value of Terminated Forward Starting Interest Rate Swap	(125)	(120)	(370)	(350)
Balance at end of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	1,429	1,919	1,429	1,919
Balance at beginning of period, Net Non current Deferred Tax Assets	73,179	31,326	70,367	31,467
Other comprehensive earnings, tax effect, Net Non current Deferred Tax Assets	(1,167)	(216)	1,645	(357)
Balance at end of period, Net Non current Deferred Tax Assets	$ 72,012	$ 31,110	$ 72,012	$ 31,110