Amounts Recognized in AOCI (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance, net of income tax	$ 4,533,220
Other comprehensive income (loss), Pretax amount	35,258	$ 2,360	$ 5,083
Other comprehensive income (loss), Income tax effect	(2,664)	(4,648)	(2,980)
Total other comprehensive income (loss), net of tax	32,594	(2,288)	2,103
Ending balance, net of income tax	4,989,514	4,533,220
Net Unrealized Gains (Losses) on Effective Cash Flow Hedges
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance, net of income tax	19	(776)
Other comprehensive income (loss), Pretax amount	6,679	1,271
Other comprehensive income (loss), Income tax effect	(2,490)	(476)
Total other comprehensive income (loss), net of tax	4,189	795
Ending balance, net of income tax	4,208	19	(776)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance, net of income tax	(14,197)	(4,159)
Other comprehensive income (loss), Pretax amount	26,678	(10,038)
Total other comprehensive income (loss), net of tax	26,678	(10,038)
Ending balance, net of income tax	12,481	(14,197)	(4,159)
Unrealized Loss on Marketable Security
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance, net of income tax	(1,398)
Other comprehensive income (loss), Pretax amount	(2,169)	(2,229)
Other comprehensive income (loss), Income tax effect	809	831
Total other comprehensive income (loss), net of tax	(1,360)	(1,398)
Ending balance, net of income tax	(2,758)	(1,398)
Minimum Pension Liability
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance, net of income tax	(9,841)	(18,194)
Other comprehensive income (loss), Pretax amount	4,070	13,356
Other comprehensive income (loss), Income tax effect	(983)	(5,003)
Total other comprehensive income (loss), net of tax	3,087	8,353
Ending balance, net of income tax	(6,754)	(9,841)	(18,194)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance, net of income tax	(25,417)	(23,129)
Ending balance, net of income tax	$ 7,177	$ (25,417)	$ (23,129)