Financial Information for Guarantor Subsidiaries and Non-Guarantor Subsidiaries - Supplemental Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Millions	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 369		$ 168
Restricted cash	44		39
Accounts receivable, net	616		599
Notes receivable, net	120		114
Inventories	238		216
Prepaid expenses, deposits and other current assets	198		233
Property and equipment, net	532		547
Operating lease right-of-use assets	113		0
Investment in subsidiaries	0		0
Goodwill	3,279		3,280
Intangible assets, net	1,660		1,809
Intercompany balances	0		0
Software, net	265		285
Other assets	498		428
Total assets	7,932		7,718
Liabilities and stockholders’ (deficit) equity
Current portion of long-term debt	45		45
Other current liabilities	688		702
Long-term debt, excluding current portion	8,802		8,992
Operating lease liabilities	95		0
Other long-term liabilities	420		442
Intercompany balances	0		0
Total liabilities and total stockholders’ (deficit) equity	(2,212)	$ (2,423)	(2,463)	$ (2,268)	$ (2,196)	$ (2,027)
Stockholders' Equity Attributable to Noncontrolling Interest	94		0
Total liabilities and total stockholders’ (deficit) equity	7,932		7,718
Non-current restricted cash	12		13
Reportable Legal Entities | SGI (Issuer)
Assets
Cash and cash equivalents	0		1
Restricted cash	1		1
Accounts receivable, net	100		79
Notes receivable, net	0		0
Inventories	47		40
Prepaid expenses, deposits and other current assets	61		63
Property and equipment, net	96		112
Operating lease right-of-use assets	25
Investment in subsidiaries	1,163		975
Goodwill	240		240
Intangible assets, net	34		34
Intercompany balances	5,868		6,054
Software, net	36		39
Other assets	419		404
Total assets	8,090		8,042
Liabilities and stockholders’ (deficit) equity
Current portion of long-term debt	42		42
Other current liabilities	173		162
Long-term debt, excluding current portion	8,793		8,991
Operating lease liabilities	21
Other long-term liabilities	23		8
Intercompany balances	0		0
Total liabilities and total stockholders’ (deficit) equity	(962)		(1,161)
Stockholders' Equity Attributable to Noncontrolling Interest	0
Total liabilities and total stockholders’ (deficit) equity	8,090		8,042
Reportable Legal Entities | SGC (Parent)
Assets
Cash and cash equivalents	235		74
Restricted cash	0		0
Accounts receivable, net	0		0
Notes receivable, net	0		0
Inventories	0		0
Prepaid expenses, deposits and other current assets	0		6
Property and equipment, net	34		31
Operating lease right-of-use assets	1
Investment in subsidiaries	3,136		2,836
Goodwill	0		0
Intangible assets, net	37		43
Intercompany balances	0		0
Software, net	48		58
Other assets	95		110
Total assets	3,586		3,158
Liabilities and stockholders’ (deficit) equity
Current portion of long-term debt	0		0
Other current liabilities	52		64
Long-term debt, excluding current portion	0		0
Operating lease liabilities	1
Other long-term liabilities	96		106
Intercompany balances	5,649		5,451
Total liabilities and total stockholders’ (deficit) equity	(2,212)		(2,463)
Stockholders' Equity Attributable to Noncontrolling Interest	0
Total liabilities and total stockholders’ (deficit) equity	3,586		3,158
Reportable Legal Entities | Guarantor Subsidiaries
Assets
Cash and cash equivalents	0		0
Restricted cash	35		32
Accounts receivable, net	195		205
Notes receivable, net	104		101
Inventories	99		82
Prepaid expenses, deposits and other current assets	61		92
Property and equipment, net	231		219
Operating lease right-of-use assets	33
Investment in subsidiaries	1,427		1,093
Goodwill	1,897		1,897
Intangible assets, net	1,186		1,291
Intercompany balances	67		0
Software, net	109		128
Other assets	41		46
Total assets	5,485		5,186
Liabilities and stockholders’ (deficit) equity
Current portion of long-term debt	2		0
Other current liabilities	242		248
Long-term debt, excluding current portion	8		0
Operating lease liabilities	28
Other long-term liabilities	605		637
Intercompany balances	0		49
Total liabilities and total stockholders’ (deficit) equity	4,600		4,252
Stockholders' Equity Attributable to Noncontrolling Interest	0
Total liabilities and total stockholders’ (deficit) equity	5,485		5,186
Non-current restricted cash	11		12
Reportable Legal Entities | Non-Guarantor Subsidiaries
Assets
Cash and cash equivalents	141		94
Restricted cash	8		6
Accounts receivable, net	321		315
Notes receivable, net	16		13
Inventories	103		111
Prepaid expenses, deposits and other current assets	75		72
Property and equipment, net	204		218
Operating lease right-of-use assets	54
Investment in subsidiaries	0		0
Goodwill	1,142		1,143
Intangible assets, net	403		441
Intercompany balances	0		0
Software, net	72		60
Other assets	376		308
Total assets	2,915		2,781
Liabilities and stockholders’ (deficit) equity
Current portion of long-term debt	1		3
Other current liabilities	255		254
Long-term debt, excluding current portion	1		1
Operating lease liabilities	45
Other long-term liabilities	168		172
Intercompany balances	286		554
Total liabilities and total stockholders’ (deficit) equity	2,065		1,797
Stockholders' Equity Attributable to Noncontrolling Interest	94
Total liabilities and total stockholders’ (deficit) equity	2,915		2,781
Non-current restricted cash	1		1
Eliminating Entries
Assets
Cash and cash equivalents	(7)		(1)
Restricted cash	0		0
Accounts receivable, net	0		0
Notes receivable, net	0		0
Inventories	(11)		(17)
Prepaid expenses, deposits and other current assets	1		0
Property and equipment, net	(33)		(33)
Operating lease right-of-use assets	0
Investment in subsidiaries	(5,726)		(4,904)
Goodwill	0		0
Intangible assets, net	0		0
Intercompany balances	(5,935)		(6,054)
Software, net	0		0
Other assets	(433)		(440)
Total assets	(12,144)		(11,449)
Liabilities and stockholders’ (deficit) equity
Current portion of long-term debt	0		0
Other current liabilities	(34)		(26)
Long-term debt, excluding current portion	0		0
Operating lease liabilities	0
Other long-term liabilities	(472)		(481)
Intercompany balances	(5,935)		(6,054)
Total liabilities and total stockholders’ (deficit) equity	(5,703)		(4,888)
Stockholders' Equity Attributable to Noncontrolling Interest	0
Total liabilities and total stockholders’ (deficit) equity	$ (12,144)		$ (11,449)