Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			$ 1,953,646
Other comprehensive income (loss) before reclassifications, net of tax			(14,123)	$ 36,683
Amounts reclassified from accumulated other comprehensive income (loss), net of tax			1,227	(468)
Other comprehensive income (loss)	$ 7,029	$ 10,086	(12,896)	36,215
Reclassification of income tax effects from the Tax Reform Act, net of tax			769
Reclassification of unrealized gains on equity securities, net of tax	(57)	(87)	1,411	(264)
Balance	1,667,760		1,667,760
ASU 2016-01
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification of unrealized gains on equity securities, net of tax			(3,125)
Foreign Currency Translation Reclassification Adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			15,919	(21,921)
Other comprehensive income (loss) before reclassifications, net of tax			(11,568)	34,235
Other comprehensive income (loss)			(11,568)	34,235
Balance	4,351	12,314	4,351	12,314
Unrealized Gains (Losses) on Marketable Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			1,362	(60)
Other comprehensive income (loss) before reclassifications, net of tax			(2,555)	2,448
Amounts reclassified from accumulated other comprehensive income (loss), net of tax			1,411	(264)
Other comprehensive income (loss)			(1,144)	2,184
Reclassification of income tax effects from the Tax Reform Act, net of tax			691
Balance	(2,216)	2,124	(2,216)	2,124
Unrealized Gains (Losses) on Marketable Securities | ASU 2016-01
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification of unrealized gains on equity securities, net of tax			(3,125)
Amortization of Prior Service Credit
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			1,495	1,767
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(61)	(68)	(184)	(204)
Other comprehensive income (loss)			(184)	(204)
Reclassification of income tax effects from the Tax Reform Act, net of tax			78
Balance	1,389	1,563	1,389	1,563
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance			18,776	(20,214)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax	(118)	(155)	1,227	(468)
Balance	$ 3,524	$ 16,001	$ 3,524	$ 16,001