Noncurrent Deferred Tax Assets Recorded in Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Equity [Abstract]
Balance at beginning of period, Pension and Postretirement Benefit Plans	$ 82,044	$ 66,467
Tax effect of other comprehensive earnings, Pension and Postretirement Benefit Plans	(1,185)	(944)
Balance at end of period, Pension and Postretirement Benefit Plans	80,859	65,523
Balance at beginning of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	749	1,290
Tax effect of other comprehensive earnings, Unamortized Value of Terminated Forward Starting Interest Rate Swap	(141)	(131)
Balance at end of period, Unamortized Value of Terminated Forward Starting Interest Rate Swap	608	1,159
Balance at beginning of period, Net Noncurrent Deferred Tax Assets	82,793	67,757
Tax effect of other comprehensive earnings, Net Noncurrent Deferred Tax Assets	(1,326)	(1,075)
Balance at end of period, Net Noncurrent Deferred Tax Assets	$ 81,467	$ 66,682