Financial Information for Guarantor Subsidiaries and Non-Guarantor Subsidiaries - Statement of Cash Flows (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Condensed Financial Statements
Net cash (used in) provided by operating activities	$ 191.9	$ 114.4
Cash flows from investing activities:
Capital expenditures	(132.6)	(142.8)
Distributions of capital on equity investments	22.5	35.2
Restricted cash	(3.8)	1.0
Changes in other assets and liabilities and other	6.1	9.5
Other, principally intercompany balances	0.0	0.0
Net cash used in investing activities	(107.8)	(98.1)
Cash flows from financing activities:
Net payments of long-term debt including repurchases of notes	(80.1)	(36.2)
Payments on license obligations	(25.0)	(18.7)
Contingent earnout payments	0.0	(0.5)
Issuance (redemptions) of common stock under stock-based compensation plans	(4.4)	0.9
Other, principally change in intercompany financing activities	0.0	0.0
Net cash provided by (used in) financing activities	(109.5)	(54.5)
Effect of exchange rate changes on cash and cash equivalents	(1.9)	(4.5)
Increase (decrease) in cash and cash equivalents	(27.3)	(42.7)
Cash and cash equivalents, beginning of period	128.7	171.8
Cash and cash equivalents, end of period	101.4	129.1
Parent Company
Cash flows from financing activities:
Issuance (redemptions) of common stock under stock-based compensation plans	(4.4)
SGI
Cash flows from financing activities:
Issuance (redemptions) of common stock under stock-based compensation plans	0.0
Guarantor Subsidiaries
Cash flows from financing activities:
Issuance (redemptions) of common stock under stock-based compensation plans	0.0
Non-Guarantor Subsidiaries
Cash flows from financing activities:
Issuance (redemptions) of common stock under stock-based compensation plans	0.0
Reportable Legal Entities | Parent Company
Condensed Financial Statements
Net cash (used in) provided by operating activities	(109.5)	(33.1)
Cash flows from investing activities:
Capital expenditures	(26.7)	(8.6)
Distributions of capital on equity investments	0.0	0.0
Restricted cash	0.0
Changes in other assets and liabilities and other	0.3	0.0
Other, principally intercompany balances	0.0	0.0
Net cash used in investing activities	(26.4)	(8.6)
Cash flows from financing activities:
Net payments of long-term debt including repurchases of notes	0.0	0.0
Payments on license obligations	(15.1)	(13.5)
Contingent earnout payments		0.0
Issuance (redemptions) of common stock under stock-based compensation plans		0.9
Other, principally change in intercompany financing activities	144.6	58.2
Net cash provided by (used in) financing activities	125.1	45.6
Effect of exchange rate changes on cash and cash equivalents	0.0	0.1
Increase (decrease) in cash and cash equivalents	(10.8)	4.0
Cash and cash equivalents, beginning of period	43.2	37.9
Cash and cash equivalents, end of period	32.4	41.9
Reportable Legal Entities | SGI
Condensed Financial Statements
Net cash (used in) provided by operating activities	122.1	(69.4)
Cash flows from investing activities:
Capital expenditures	(5.2)	(12.4)
Distributions of capital on equity investments	0.0	0.8
Restricted cash	0.0
Changes in other assets and liabilities and other	0.0	0.0
Other, principally intercompany balances	(39.9)	114.2
Net cash used in investing activities	(45.1)	102.6
Cash flows from financing activities:
Net payments of long-term debt including repurchases of notes	(76.5)	(31.5)
Payments on license obligations	0.0	0.0
Contingent earnout payments		0.0
Issuance (redemptions) of common stock under stock-based compensation plans		0.0
Other, principally change in intercompany financing activities	0.0	0.0
Net cash provided by (used in) financing activities	(76.5)	(31.5)
Effect of exchange rate changes on cash and cash equivalents	0.0	(0.4)
Increase (decrease) in cash and cash equivalents	0.5	1.3
Cash and cash equivalents, beginning of period	0.0	0.1
Cash and cash equivalents, end of period	0.5	1.4
Reportable Legal Entities | Guarantor Subsidiaries
Condensed Financial Statements
Net cash (used in) provided by operating activities	104.8	127.7
Cash flows from investing activities:
Capital expenditures	(77.3)	(95.6)
Distributions of capital on equity investments	0.0	0.0
Restricted cash	(3.8)
Changes in other assets and liabilities and other	8.0	4.0
Other, principally intercompany balances	0.0	0.0
Net cash used in investing activities	(73.1)	(91.6)
Cash flows from financing activities:
Net payments of long-term debt including repurchases of notes	0.0	0.0
Payments on license obligations	(9.9)	(5.2)
Contingent earnout payments		(0.5)
Issuance (redemptions) of common stock under stock-based compensation plans		(29.6)
Other, principally change in intercompany financing activities	(25.9)	(12.0)
Net cash provided by (used in) financing activities	(35.8)	(47.3)
Effect of exchange rate changes on cash and cash equivalents	(0.6)	(1.8)
Increase (decrease) in cash and cash equivalents	(4.7)	(13.0)
Cash and cash equivalents, beginning of period	4.7	28.8
Cash and cash equivalents, end of period	0.0	15.8
Reportable Legal Entities | Non-Guarantor Subsidiaries
Condensed Financial Statements
Net cash (used in) provided by operating activities	74.5	89.2
Cash flows from investing activities:
Capital expenditures	(23.4)	(26.2)
Distributions of capital on equity investments	22.5	34.4
Restricted cash	0.0
Changes in other assets and liabilities and other	(2.2)	5.5
Other, principally intercompany balances	0.0	0.0
Net cash used in investing activities	(3.1)	13.7
Cash flows from financing activities:
Net payments of long-term debt including repurchases of notes	(3.6)	(4.7)
Payments on license obligations	0.0	0.0
Contingent earnout payments		0.0
Issuance (redemptions) of common stock under stock-based compensation plans		(116.0)
Other, principally change in intercompany financing activities	(78.8)	(14.8)
Net cash provided by (used in) financing activities	(82.4)	(135.5)
Effect of exchange rate changes on cash and cash equivalents	(1.3)	(2.4)
Increase (decrease) in cash and cash equivalents	(12.3)	(35.0)
Cash and cash equivalents, beginning of period	80.8	105.0
Cash and cash equivalents, end of period	68.5	70.0
Eliminating Entries
Condensed Financial Statements
Net cash (used in) provided by operating activities	0.0	0.0
Cash flows from investing activities:
Capital expenditures	0.0	0.0
Distributions of capital on equity investments	0.0	0.0
Restricted cash	0.0
Changes in other assets and liabilities and other	0.0	0.0
Other, principally intercompany balances	39.9	(114.2)
Net cash used in investing activities	39.9	(114.2)
Cash flows from financing activities:
Net payments of long-term debt including repurchases of notes	0.0	0.0
Payments on license obligations	0.0	0.0
Contingent earnout payments		0.0
Issuance (redemptions) of common stock under stock-based compensation plans	0.0	145.6
Other, principally change in intercompany financing activities	(39.9)	(31.4)
Net cash provided by (used in) financing activities	(39.9)	114.2
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Increase (decrease) in cash and cash equivalents	0.0	0.0
Cash and cash equivalents, beginning of period	0.0	0.0
Cash and cash equivalents, end of period	$ 0.0	$ 0.0