Supplemental Stockholders' Equity Information - Changes in Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 28, 2020	Jun. 30, 2019	Jun. 28, 2020	Jun. 30, 2019
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period	$ 1,193,574	$ 1,059,814	$ 1,173,863	$ 1,042,641
Other comprehensive income before reclassifications, before tax			5,155
Amounts reclassified from accumulated other comprehensive loss, before tax			12,628
Income tax expense	2,848	2,015	4,763	3,414
Other comprehensive income, net of tax	8,077	5,818	13,020	9,740
Balance, end of period	1,231,031	1,085,203	1,231,031	1,085,203
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period			3,438
Other comprehensive income before reclassifications, before tax			365
Amounts reclassified from accumulated other comprehensive loss, before tax			0
Income tax expense			97
Other comprehensive income, net of tax			268
Balance, end of period	3,706		3,706
Funded Status of Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period			(498,986)
Other comprehensive income before reclassifications, before tax			0
Amounts reclassified from accumulated other comprehensive loss, before tax			12,628
Income tax expense			3,390
Other comprehensive income, net of tax			9,238
Balance, end of period	(489,748)		(489,748)
Net Unrealized Gain on Available-For-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period			572
Other comprehensive income before reclassifications, before tax			4,790
Amounts reclassified from accumulated other comprehensive loss, before tax			0
Income tax expense			1,276
Other comprehensive income, net of tax			3,514
Balance, end of period	4,086		4,086
Accumulated Other Comprehensive Loss, Net of Income Taxes
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance, beginning of period	(490,033)	(513,802)	(494,976)	(517,724)
Other comprehensive income, net of tax	8,077	5,818	13,020	9,740
Balance, end of period	$ (481,956)	$ (507,984)	$ (481,956)	$ (507,984)