Deferred Revenue - Narrative (Details) - USD ($) $ in Thousands			12 Months Ended
	Jan. 01, 2017	Jan. 01, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue Recognition and Deferred Revenue [Abstract]
Deferred revenue, revenue recognized	$ 114,000	$ 98,000	$ 839,000	$ 879,000
Total			264,000	237,000	$ 190,000
Deferred revenue, current			121,000	114,000
Deferred revenue, noncurrent			$ 143,000	$ 123,000