Consolidated Statements of Cash Flows (Parenthetical)	Sep. 30, 2017	Dec. 15, 2016	Sep. 30, 2016	Dec. 15, 2015	Oct. 13, 2015	Sep. 30, 2015
Senior Notes – 6.000%
Interest rate					6.00%
Senior Notes | Senior Notes – 5.250%
Interest rate	5.25%	5.25%
Senior Notes | Senior Notes – 6.000%
Interest rate	6.00%		6.00%		6.00%
Senior Notes | Senior Notes – 6.625%
Interest rate			6.625%	6.625%		6.625%