Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Equity [Abstract]
Balance at beginning of period, Pension and Postretirement Benefit Plans	$ 67,552	$ 29,016	$ 68,568	$ 29,198
Other comprehensive earnings, tax effect, Pension and Postretirement Benefit Plans	4,073	271	3,057	89
Balance at end of period, Pension and Postretirement Benefit Plans	71,625	29,287	71,625	29,287
Balance at beginning of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	1,679	2,155	1,799	2,269
Other comprehensive earnings, tax effect, Unamortized Value of Terminated Forward Starting Interest Rate Swap	(125)	(116)	(245)	(230)
Balance at end of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	1,554	2,039	1,554	2,039
Balance at beginning of period, Net Non current Deferred Tax Assets	69,231	31,171	70,367	31,467
Other comprehensive earnings, tax effect, Net Non current Deferred Tax Assets	3,948	155	2,812	(141)
Balance at end of period, Net Non current Deferred Tax Assets	$ 73,179	$ 31,326	$ 73,179	$ 31,326