Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period, Pension and Postretirement Benefit Plans	$ 69,842	$ 53,328	$ 70,881	$ 55,161
Other comprehensive earnings, tax effect, Pension and Postretirement Benefit Plans	(1,566)	(1,026)	(2,605)	(2,859)
Balance at end of period, Pension and Postretirement Benefit Plans	68,276	52,302	68,276	52,302
Balance at beginning of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	2,492	2,915	2,707	3,116
Other comprehensive earnings, tax effect, Unamortized Value of Terminated Forward Starting Interest Rate Swap	(111)	(103)	(326)	(304)
Balance at end of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	2,381	2,812	2,381	2,812
Balance at beginning of period, Net Non current Deferred Tax Assets	72,334	56,243	73,588	58,277
Other comprehensive earnings, tax effect, Net Non current Deferred Tax Assets	(1,677)	(1,129)	(2,931)	(3,163)
Balance at end of period, Net Non current Deferred Tax Assets	$ 70,657	$ 55,114	$ 70,657	$ 55,114