Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 25, 2016	Dec. 27, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ 10,028	$ 13,941	$ 16,324
Gross additions to tax positions taken during the current year	9,009	997	1,151
Gross additions to tax positions taken during the prior year	103	0	282
Gross reductions to tax positions taken during the prior year	(372)	(3,042)	(37)
Reductions from lapse of applicable statutes of limitations	(1,682)	(1,868)	(3,779)
Balance at end of year	$ 17,086	$ 10,028	$ 13,941