Capital Stock Quarterly Dividend (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 29, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 28, 2014
Quarterly Cash Dividend [Line Items]
Common stock dividends	$ 21,612	$ 22,510	$ 22,959	$ 23,215	$ 23,555	$ 23,620	$ 24,100	$ 0	$ 90,296	$ 71,275
Regular Cash Dividend
Quarterly Cash Dividend [Line Items]
Dividends declared (usd per share)	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0.25	$ 0	$ 1.0	$ 0.75	$ 0