Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions				9 Months Ended	12 Months Ended
	Oct. 31, 2016	Oct. 28, 2016	Jul. 29, 2016	Sep. 30, 2016	Dec. 31, 2015
Subsequent event
Dividend declared (in dollars per share)			$ 0.06	$ 0.06	$ 0.06
Subsequent Event
Subsequent event
Dividend declared (in dollars per share)		$ 0.06
Subsequent Event | Joint Venture Saudi Aramco
Subsequent event
Total initial value of the investment per party	$ 500.0