Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 28, 2014	Jun. 29, 2013	Jun. 28, 2014	Jun. 29, 2013
Statement of Partners' Capital [Abstract]
Net income, as reported	$ 8,530	$ 8,294	$ 13,810	$ 16,649
Other comprehensive income (loss), net of tax:
Unrealized gains/(losses) on investments, net of tax	45	(173)	(91)	(161)
Total comprehensive income	$ 8,575	$ 8,121	$ 13,719	$ 16,488