Changes in Operations and Non-operating Items Non-Operating Items (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2016	[1]	Sep. 30, 2016	[1]	Jun. 30, 2016	[1]	Mar. 31, 2016	[1]	Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 29, 2015		Dec. 31, 2016		Dec. 31, 2015		Dec. 28, 2014
Changes in Operations and Non-Operating Items [Abstract]
Loss on extinguishment of debt									$ 0		$ 0		$ (37,040)		$ 0		$ 0		$ (37,040)		$ 0
Gain on investment transactions, net									103	[1]	3,250	[1]	8,133	[1]	687	[1]	0		12,173	[1]	371,785
Other non-operating gain (loss), net	$ 4,949		$ 57		$ (75)		$ 496		$ 5,623	[1]	$ 1,396	[1]	$ 209	[1]	$ 0	[1]	5,427	[1]	7,228	[1]	(4,804)
Nonoperating Income (Expense)																	$ 5,427		$ (17,639)		$ 366,981

[1] See Note 5 to the Company’s consolidated financial statements for information pertaining to non-operating items recorded in 2016 and 2015.