Fair Value Measurements - Schedule of Changes in Level 3 Assets and Liabilities (Details) - Level 3 [Member] - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period - assets	$ 292.6	$ 321.8
Total realized and unrealized gains (losses) - assets	(3.6)	0.0
Purchases - assets	23.2	2.5
Sales - assets	(6.5)	(9.6)
Foreign exchange revaluation	(3.8)	(2.7)
Balance at End of Period - assets	256.0	312.0
Change in unrealized gains (losses) included in net income relating to assets and liabilities held at period end	(3.6)	(0.8)
Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period - assets	205.1	20.7
Purchases - assets	0.5	3.3
Sales - assets	(2.4)	0.0
Settlements - assets	(1.7)	(0.8)
Foreign exchange revaluation	(3.4)	0.0
Balance at End of Period - assets	198.7	23.8
Change in unrealized gains (losses) included in net income relating to assets and liabilities held at period end	(0.1)	0.2
Contingent Consideration Liability [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period - liabilities	(98.1)	(102.9)
Purchases - liabilities	0.0	0.0
Sales - liabilities	0.0	0.0
Settlements - liabilities	2.2	3.3
Foreign exchange revaluation	0.0	0.0
Balance at End of Period - liabilities	(83.7)	(115.8)
Change in unrealized gains (losses) included in net income relating to assets and liabilities held at period end	12.2	(16.2)
Investment and other income [Member] | Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total realized and unrealized gains (losses) - assets	0.6	0.6
Investment and other income [Member] | Contingent Consideration Liability [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total realized and unrealized gains (losses) - liabilities	0.0	0.0
General, administrative and other expense [Member] | Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total realized and unrealized gains (losses) - assets	0.0	0.0
General, administrative and other expense [Member] | Contingent Consideration Liability [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total realized and unrealized gains (losses) - liabilities	$ 12.2	$ (16.2)