Financial Information for Guarantor Subsidiaries and Non-Guarantor Subsidiaries - Supplemental Condensed Consolidating Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Condensed Financial Statements
Net cash (used in) provided by operating activities	$ 111.0	$ 101.1
Cash flows from investing activities:
Capital expenditures	(61.3)	(51.2)
Acquisition of business, net of cash acquired	(21.5)	0.0
Distributions of capital from equity investments	1.3	1.5
Changes in other assets and liabilities and other	2.0	1.5
Other, principally intercompany balances	0.0	0.0
Net cash used in investing activities	(79.5)	(48.2)
Cash flows from financing activities:
Net payments of long-term debt including proceeds and repurchases of senior notes and term loans	22.5	(27.5)
Payments of debt issuance and deferred financing costs	(27.2)	0.0
Payments on license obligations	(9.8)	(9.6)
Issuance (redemptions) of common stock under stock-based compensation plans	(0.6)	0.0
Other, principally change in intercompany financing activities	0.0	0.0
Net cash provided by (used in) financing activities	(15.1)	(37.1)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	2.5	1.8
Increase (decrease) in cash, cash equivalents and restricted cash	18.9	17.6
Cash, cash equivalents and restricted cash, beginning of period	156.9	166.8
Cash, cash equivalents and restricted cash, end of period	175.8	184.4
Eliminating Entries
Condensed Financial Statements
Net cash (used in) provided by operating activities	(4.5)	(0.8)
Cash flows from investing activities:
Capital expenditures	0.0	0.0
Acquisition of business, net of cash acquired	0.0
Distributions of capital from equity investments	0.0	0.0
Changes in other assets and liabilities and other	0.0	0.0
Other, principally intercompany balances	282.5	(65.4)
Net cash used in investing activities	282.5	(65.4)
Cash flows from financing activities:
Net payments of long-term debt including proceeds and repurchases of senior notes and term loans	0.0	0.0
Payments of debt issuance and deferred financing costs	0.0
Payments on license obligations	0.0	0.0
Issuance (redemptions) of common stock under stock-based compensation plans	0.0
Other, principally change in intercompany financing activities	(282.5)	65.4
Net cash provided by (used in) financing activities	(282.5)	65.4
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.0	0.0
Increase (decrease) in cash, cash equivalents and restricted cash	(4.5)	(0.8)
Cash, cash equivalents and restricted cash, beginning of period	(1.1)	0.0
Cash, cash equivalents and restricted cash, end of period	(5.6)	(0.8)
SGC (Parent and Issuer) | Reportable Legal Entities
Condensed Financial Statements
Net cash (used in) provided by operating activities	(62.2)	(75.2)
Cash flows from investing activities:
Capital expenditures	(9.3)	(5.8)
Acquisition of business, net of cash acquired	0.0
Distributions of capital from equity investments	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 investing activities	(9.3)	(5.8)
Cash flows from financing activities:
Net payments of long-term debt including proceeds and repurchases of senior notes and term loans	(250.0)	0.0
Payments of debt issuance and deferred financing costs	0.0
Payments on license obligations	(9.2)	(8.4)
Issuance (redemptions) of common stock under stock-based compensation plans	(0.6)
Other, principally change in intercompany financing activities	336.4	108.0
Net cash provided by (used in) financing activities	76.6	99.6
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.0	0.0
Increase (decrease) in cash, cash equivalents and restricted cash	5.1	18.6
Cash, cash equivalents and restricted cash, beginning of period	32.7	43.2
Cash, cash equivalents and restricted cash, end of period	37.8	61.8
SGI (Issuer)
Cash flows from financing activities:
Issuance (redemptions) of common stock under stock-based compensation plans	0.0
SGI (Issuer) | Reportable Legal Entities
Condensed Financial Statements
Net cash (used in) provided by operating activities	(20.9)	(36.9)
Cash flows from investing activities:
Capital expenditures	(4.7)	(2.7)
Acquisition of business, net of cash acquired	0.0
Distributions of capital from equity investments	0.0	0.0
Changes in other assets and liabilities and other	0.0	0.0
Other, principally intercompany balances	(221.9)	65.4
Net cash used in investing activities	(226.6)	62.7
Cash flows from financing activities:
Net payments of long-term debt including proceeds and repurchases of senior notes and term loans	274.0	(25.8)
Payments of debt issuance and deferred financing costs	(27.2)
Payments on license obligations	0.0	0.0
Other, principally change in intercompany financing activities	0.0	0.0
Net cash provided by (used in) financing activities	246.8	(25.8)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.0	0.1
Increase (decrease) in cash, cash equivalents and restricted cash	(0.7)	0.1
Cash, cash equivalents and restricted cash, beginning of period	1.7	0.0
Cash, cash equivalents and restricted cash, end of period	1.0	0.1
Guarantor Subsidiaries
Cash flows from financing activities:
Issuance (redemptions) of common stock under stock-based compensation plans	0.0
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Financial Statements
Net cash (used in) provided by operating activities	104.3	176.0
Cash flows from investing activities:
Capital expenditures	(26.2)	(35.5)
Acquisition of business, net of cash acquired	(21.5)
Distributions of capital from equity investments	0.0	0.0
Changes in other assets and liabilities and other	0.0	1.6
Other, principally intercompany balances	0.0	0.0
Net cash used in investing activities	(47.7)	(33.9)
Cash flows from financing activities:
Net payments of long-term debt including proceeds and repurchases of senior notes and term loans	0.0	0.0
Payments of debt issuance and deferred financing costs	0.0
Payments on license obligations	(0.6)	(1.2)
Other, principally change in intercompany financing activities	(53.9)	(140.8)
Net cash provided by (used in) financing activities	(54.5)	(142.0)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.0	0.0
Increase (decrease) in cash, cash equivalents and restricted cash	2.1	0.1
Cash, cash equivalents and restricted cash, beginning of period	41.0	37.7
Cash, cash equivalents and restricted cash, end of period	43.1	37.8
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Financial Statements
Net cash (used in) provided by operating activities	94.3	38.0
Cash flows from investing activities:
Capital expenditures	(21.1)	(7.2)
Acquisition of business, net of cash acquired	0.0
Distributions of capital from equity investments	1.3	1.5
Changes in other assets and liabilities and other	2.0	(0.1)
Other, principally intercompany balances	(60.6)	0.0
Net cash used in investing activities	(78.4)	(5.8)
Cash flows from financing activities:
Net payments of long-term debt including proceeds and repurchases of senior notes and term loans	(1.5)	(1.7)
Payments of debt issuance and deferred financing costs	0.0
Payments on license obligations	0.0	0.0
Issuance (redemptions) of common stock under stock-based compensation plans	0.0
Other, principally change in intercompany financing activities	0.0	(32.6)
Net cash provided by (used in) financing activities	(1.5)	(34.3)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	2.5	1.7
Increase (decrease) in cash, cash equivalents and restricted cash	16.9	(0.4)
Cash, cash equivalents and restricted cash, beginning of period	82.6	85.9
Cash, cash equivalents and restricted cash, end of period	$ 99.5	$ 85.5