Related Person Transactions - Related/Corvex (Details) - Related/Corvex - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended
	Aug. 31, 2016	Aug. 31, 2015	Dec. 31, 2014	Jul. 31, 2014
Related Party Transaction [Line Items]
Amount of reimbursements payable to related party				$ 33.5
Reimbursement amount paid	$ 8.2	$ 8.4	$ 16.7
Amount of reimbursements payable to related party if specified minimum common share price maintain during the one year period after the date on which the reimbursement is approved by shareholders				8.4
Amount of reimbursements payable to related party if specified minimum common share price maintain during the one year period between the first and second anniversaries of the date on which the reimbursement is approved by shareholders				$ 8.4
Minimum
Related Party Transaction [Line Items]
Price per common share during one year period after date (in dollars per share)				$ 26.00
Price per common share during first and second year after date (in dollars per share)				$ 26.00