Revenue From Contracts With Customers - Cumulative Effect of Adoption (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 30, 2017
Current liabilities:
Deferred revenue	$ 52,500	$ 49,009	$ 62,993
Total current liabilities	221,663	197,325	211,309
Other non-current liabilities:
Deferred revenue	20,200	19,430	31,222
Deferred income taxes, net	87,282	80,252	73,648
Total other non-current liabilities	149,614	145,726	150,914
Stockholders’ equity:
Retained earnings	81,219	56,317	37,145
Total stockholders’ equity	711,275	678,760	659,588
Without ASC 606 Adoption
Current liabilities:
Deferred revenue	67,303		62,993
Total current liabilities	236,466		211,309
Other non-current liabilities:
Deferred revenue	31,992		31,222
Deferred income taxes, net	80,468		73,648
Total other non-current liabilities	154,592		150,914
Stockholders’ equity:
Retained earnings	61,438		37,145
Total stockholders’ equity	691,494		$ 659,588
Impact of Adoption | ASU No. 2014-09
Current liabilities:
Deferred revenue	(14,803)	(13,984)
Total current liabilities	(14,803)	(13,984)
Other non-current liabilities:
Deferred revenue	(11,792)	(11,792)
Deferred income taxes, net	6,814	6,604
Total other non-current liabilities	(4,978)	(5,188)
Stockholders’ equity:
Retained earnings	19,781	19,172
Total stockholders’ equity	$ 19,781	$ 19,172