Revenue Recognition (Balance Sheet Impact) (Details) - USD ($) $ in Thousands	Apr. 01, 2018	Jan. 01, 2018	Dec. 31, 2017
Assets:
Accounts receivable, net	$ 317,102	$ 418,911	$ 412,798
Inventories	266,345	243,526	245,894
Other non-current assets	85,953	66,133	61,789
Liabilities:
Accounts payable	96,371	111,759	111,915
Other accrued liabilities	239,261	267,951	222,470
Deferred revenue	30,985	30,103	55,284
Income taxes payable	9,866	7,739	7,015
Other non-current liabilities	23,213	21,823	22,099
Stockholders’ equity:
Retained earnings	140,080	115,665	128,168
Adjustments | Accounting Standards Update 2014-09
Assets:
Accounts receivable, net	(13,258)	6,113
Inventories	2,166	(2,368)
Other non-current assets	(4,504)	4,344
Liabilities:
Accounts payable	286	(156)
Other accrued liabilities	(48,671)	45,481
Deferred revenue	18,825	(25,181)
Income taxes payable	(528)	724
Other non-current liabilities	273	(276)
Stockholders’ equity:
Retained earnings	14,219	$ (12,503)
Balance without adoption of ASC 606
Assets:
Accounts receivable, net	303,844		412,798
Inventories	268,511		245,894
Other non-current assets	81,449		61,789
Liabilities:
Accounts payable	96,657		111,915
Other accrued liabilities	190,590		222,470
Deferred revenue	49,810		55,284
Income taxes payable	9,338		7,015
Other non-current liabilities	23,486		22,099
Stockholders’ equity:
Retained earnings	$ 154,299		$ 128,168