Common Shares (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jan. 03, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common Shares
Shares repurchased		3,100,000	300,000
Total aggregate amount of shares purchased		$ 18,100	$ 1,700
Capital Units, Authorized		825,000,000
Common Stock, Shares Authorized		800,000,000	800,000,000
Common Stock, Par or Stated Value Per Share		$ 0.001	$ 0.001
Preferred Stock, Shares Authorized		25,000,000
Preferred shares, par value (in dollars per share)		$ 0.001
Preferred shares, shares issued		0
Preferred Stock, Shares Outstanding		0
Treasury shares reissued during the year		0	0	0
Common stock dividend declared per quarter (in dollars per share)		$ 0.06	$ 0.06
Cash dividends paid	$ 17,100	$ 68,503	$ 50,924	$ 69,363
Officers and Directors
Common Shares
Restricted stock awarded to executive officers, key employees & directors		1,989,915	3,919,696	3,530,033
Restricted shares awarded, average market price (in dollars per share)		$ 13.08	$ 9.85	$ 10.09