Segment and Geographic Information - Total Revenues by Geographic Location (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Revenues	$ 2,777.6	$ 4,868.5	$ 3,708.9	$ 3,399.9	$ 2,628.4	$ 3,995.1	$ 14,442.0	$ 13,627.7	$ 14,754.9	$ 34,693.2	$ 34,022.4
Gross Profit	178.6	$ 175.0	$ 166.1	$ 151.3	178.7	$ 151.6	$ 156.5	$ 137.5	671.0	624.3	490.9
Long-Lived Assets	29.4				19.7				29.4	19.7	15.9
UNITED STATES
Revenues									817.1	25,959.0	19,055.3
Gross Profit									457.0	424.3	330.4
Long-Lived Assets	23.3				13.8				23.3	13.8	8.5
Europe [Member]
Revenues									463.5	121.2	86.0
Gross Profit									120.2	125.0	86.0
Long-Lived Assets	4.8				4.0				4.8	4.0	5.0
South America [Member]
Revenues									64.8	49.0	53.2
Gross Profit									64.8	49.0	53.2
Long-Lived Assets	1.2				1.7				1.2	1.7	2.0
Asia [Member]
Revenues									13,405.1	8,560.0	14,822.4
Gross Profit									24.6	21.9	15.8
Long-Lived Assets	0.1				0.2				0.1	0.2	0.3
Other (geographic location) [Member]
Revenues									4.4	4.0	5.5
Gross Profit									4.4	4.1	5.5
Long-Lived Assets	$ 0.0				$ 0.0				$ 0.0	$ 0.0	$ 0.1