Earnings per Unit (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 28, 2014	Sep. 29, 2013	Sep. 28, 2014	Sep. 29, 2013	Sep. 28, 2014	Sep. 29, 2013
Basic weighted average units outstanding	55,439	55,485	55,448	55,472	55,458	55,460
Effect of dilutive units:
Unit options and restricted unit awards	336	189	317	146	290	120
Phantom units	80	189	90	185	116	224
Diluted weighted average units outstanding	55,855	55,863	55,855	55,803	55,864	55,804
Net income (loss) per limited partner unit - basic	$ 2.92	$ 3.43	$ 2.21	$ 2.32	$ 1.84	$ 2.13
Net income (loss) per limited partner unit - diluted	$ 2.90	$ 3.41	$ 2.19	$ 2.31	$ 1.82	$ 2.12