Revenue Recognition (Balance Sheet Impact) (Details) - USD ($) $ in Thousands	Jul. 01, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets:
Accounts receivable, net	$ 343,883	$ 418,911	$ 412,798
Inventories	291,459	243,526	245,894
Other non-current assets	86,149	66,133	61,789
Liabilities:
Accounts payable	107,704	111,759	111,915
Other accrued liabilities	265,990	267,951	222,470
Deferred revenue	30,674	30,103	55,284
Income taxes payable	1,359	7,739	7,015
Other non-current liabilities	24,144	21,823	22,099
Stockholders’ equity:
Retained earnings	129,953	115,665	128,168
Adjustments | Accounting Standards Update 2014-09
Assets:
Accounts receivable, net	(14,167)	6,113
Inventories	1,923	(2,368)
Other non-current assets	(4,677)	4,344
Liabilities:
Accounts payable	136	(156)
Other accrued liabilities	(48,237)	45,481
Deferred revenue	15,763	(25,181)
Income taxes payable	(294)	724
Other non-current liabilities	721	(276)
Stockholders’ equity:
Retained earnings	14,990	$ (12,503)
Balance without adoption of ASC 606
Assets:
Accounts receivable, net	329,716		412,798
Inventories	293,382		245,894
Other non-current assets	81,472		61,789
Liabilities:
Accounts payable	107,840		111,915
Other accrued liabilities	217,753		222,470
Deferred revenue	46,437		55,284
Income taxes payable	1,065		7,015
Other non-current liabilities	24,865		22,099
Stockholders’ equity:
Retained earnings	$ 144,943		$ 128,168