Financial Information for Guarantor Subsidiaries and Non-Guarantor Subsidiaries - Statement of Cash Flows (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Condensed Financial Statements
Net cash (used in) provided by operating activities	$ 342.8	$ 255.5
Cash flows from investing activities:
Capital expenditures	(214.4)	(233.6)
Distributions of capital on equity investments	24.0	37.0
Restricted cash	(3.5)	9.3
Changes in other assets and liabilities and other	6.1	10.1
Other, principally intercompany balances	0.0	0.0
Net cash (used in) provided by investing activities	(187.8)	(177.2)
Cash flows from financing activities:
Net payments of long-term debt including repurchases of notes	(122.5)	(108.8)
Payments on license obligations	(34.5)	(32.0)
Contingent earnout payments	0.0	(0.5)
Issuance (redemptions) of common stock under stock-based compensation plans	(4.7)	0.4
Other, principally change in intercompany financing activities	0.0	0.0
Net cash provided by (used in) financing activities	(161.7)	(140.9)
Effect of exchange rate changes on cash and cash equivalents	(1.1)	(7.1)
(Decrease) increase in cash and cash equivalents	(7.8)	(69.7)
Cash and cash equivalents, beginning of period	128.7	171.8
Cash and cash equivalents, end of period	120.9	102.1
SGI (Issuer)
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
Reportable Legal Entities | SGC (Parent and Issuer)
Condensed Financial Statements
Net cash (used in) provided by operating activities	(213.3)	(26.7)
Cash flows from investing activities:
Capital expenditures	(36.6)	(12.8)
Distributions of capital on equity investments	0.0	0.0
Restricted cash	0.0	0.0
Changes in other assets and liabilities and other	0.0	0.0
Other, principally intercompany balances	0.0	0.0
Net cash (used in) provided by investing activities	(36.6)	(12.8)
Cash flows from financing activities:
Net payments of long-term debt including repurchases of notes	0.0	0.0
Payments on license obligations	(24.2)	(19.5)
Contingent earnout payments		0.0
Issuance (redemptions) of common stock under stock-based compensation plans	(4.7)	0.5
Other, principally change in intercompany financing activities	278.3	37.9
Net cash provided by (used in) financing activities	249.4	18.9
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
(Decrease) increase in cash and cash equivalents	(0.5)	(20.6)
Cash and cash equivalents, beginning of period	43.2	37.9
Cash and cash equivalents, end of period	42.7	17.3
Reportable Legal Entities | SGI (Issuer)
Condensed Financial Statements
Net cash (used in) provided by operating activities	(157.0)	(339.9)
Cash flows from investing activities:
Capital expenditures	(22.1)	(19.7)
Distributions of capital on equity investments	0.0	1.0
Restricted cash	0.0	0.0
Changes in other assets and liabilities and other	0.0	(0.1)
Other, principally intercompany balances	296.8	461.4
Net cash (used in) provided by investing activities	274.7	442.6
Cash flows from financing activities:
Net payments of long-term debt including repurchases of notes	(117.2)	(102.3)
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	(117.2)	(102.3)
Effect of exchange rate changes on cash and cash equivalents	0.0	(0.5)
(Decrease) increase in cash and cash equivalents	0.5	(0.1)
Cash and cash equivalents, beginning of period	0.0	0.1
Cash and cash equivalents, end of period	0.5	0.0
Reportable Legal Entities | Guarantor Subsidiaries
Condensed Financial Statements
Net cash (used in) provided by operating activities	494.3	454.6
Cash flows from investing activities:
Capital expenditures	(110.4)	(168.0)
Distributions of capital on equity investments	0.0	0.0
Restricted cash	(3.5)	9.3
Changes in other assets and liabilities and other	6.1	5.1
Other, principally intercompany balances	0.0	0.0
Net cash (used in) provided by investing activities	(107.8)	(153.6)
Cash flows from financing activities:
Net payments of long-term debt including repurchases of notes	0.0	0.0
Payments on license obligations	(10.3)	(12.5)
Contingent earnout payments		(0.5)
Issuance (redemptions) of common stock under stock-based compensation plans		(37.1)
Other, principally change in intercompany financing activities	(376.3)	(270.6)
Net cash provided by (used in) financing activities	(386.6)	(320.7)
Effect of exchange rate changes on cash and cash equivalents	(0.4)	(0.8)
(Decrease) increase in cash and cash equivalents	(0.5)	(20.5)
Cash and cash equivalents, beginning of period	0.5	27.3
Cash and cash equivalents, end of period	0.0	6.8
Reportable Legal Entities | Non-Guarantor Subsidiaries
Condensed Financial Statements
Net cash (used in) provided by operating activities	225.9	167.5
Cash flows from investing activities:
Capital expenditures	(45.3)	(33.1)
Distributions of capital on equity investments	24.0	36.0
Restricted cash	0.0	0.0
Changes in other assets and liabilities and other	0.0	5.1
Other, principally intercompany balances	(198.8)	0.0
Net cash (used in) provided by investing activities	(220.1)	8.0
Cash flows from financing activities:
Net payments of long-term debt including repurchases of notes	(5.3)	(6.5)
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	(110.2)
Other, principally change in intercompany financing activities	0.0	(81.5)
Net cash provided by (used in) financing activities	(5.3)	(198.2)
Effect of exchange rate changes on cash and cash equivalents	(0.7)	(5.8)
(Decrease) increase in cash and cash equivalents	(0.2)	(28.5)
Cash and cash equivalents, beginning of period	85.0	106.5
Cash and cash equivalents, end of period	84.8	78.0
Eliminating Entries
Condensed Financial Statements
Net cash (used in) provided by operating activities	(7.1)	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	0.0
Changes in other assets and liabilities and other	0.0	0.0
Other, principally intercompany balances	(98.0)	(461.4)
Net cash (used in) provided by investing activities	(98.0)	(461.4)
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	147.2
Other, principally change in intercompany financing activities	98.0	314.2
Net cash provided by (used in) financing activities	98.0	461.4
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
(Decrease) increase in cash and cash equivalents	(7.1)	0.0
Cash and cash equivalents, beginning of period	0.0	0.0
Cash and cash equivalents, end of period	$ (7.1)	$ 0.0