Common Shares (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions		3 Months Ended		6 Months Ended
	Apr. 21, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Common Shares
Shares repurchased					0.3
Repurchase of treasury shares					$ 1,687
Dividends paid				$ 34,307	$ 33,925
Common shares
Common stock dividend declared (in dollars per share)	$ 0.06	$ 0.06	$ 0.06	$ 0.06	$ 0.06
Cash dividends paid				$ 34,197	$ 16,922