Consolidated Statements of Equity (unaudited) - USD ($) $ in Millions		Total	Common Stock	Treasury Stock		Additional Paid-in Capital	Accumulated Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2017			71,900,000	100,000
Beginning balance at Dec. 31, 2017		$ 492.0	$ 0.7	$ (3.4)		$ 29.9	$ 548.7	$ (85.7)	$ 1.8
Increase (Decrease) in Stockholders' Equity
Net income (loss)		(8.8)					(9.1)		0.3
Issuance of common stock in connection with stock plans (in shares)	[1]		100,000
Issuance of common stock in connection with stock plans	[1]	0.0
Share-based compensation		5.3				5.3
Exercise of stock options (in shares)			400,000
Exercise of stock options		$ 5.2				5.2
Share repurchases (in shares)		45,000		100,000	[2]
Share repurchases	[2]	$ (1.3)		$ (1.3)
Other comprehensive income (loss)		(27.6)						(27.6)
Dividends and other changes in noncontrolling interest		(0.1)							(0.1)
Ending balance (in shares) at Sep. 30, 2018			72,400,000	200,000
Ending balance at Sep. 30, 2018		464.7	$ 0.7	$ (4.7)		40.4	539.6	(113.3)	2.0
Beginning balance (in shares) at Jun. 30, 2018			72,400,000	200,000
Beginning balance at Jun. 30, 2018		448.6	$ 0.7	$ (4.7)		40.8	514.2	(104.4)	2.0
Increase (Decrease) in Stockholders' Equity
Net income (loss)		25.5					25.4		0.1
Share-based compensation		(0.5)				(0.5)
Exercise of stock options		$ 0.1				0.1
Share repurchases (in shares)		56
Other comprehensive income (loss)		$ (8.9)						(8.9)
Dividends and other changes in noncontrolling interest		(0.1)							(0.1)
Ending balance (in shares) at Sep. 30, 2018			72,400,000	200,000
Ending balance at Sep. 30, 2018		464.7	$ 0.7	$ (4.7)		40.4	539.6	(113.3)	2.0
Beginning balance (in shares) at Dec. 31, 2018			72,400,000	200,000
Beginning balance at Dec. 31, 2018		481.4	$ 0.7	$ (4.8)		39.6	563.9	(120.0)	2.0
Increase (Decrease) in Stockholders' Equity
Net income (loss)		40.9					40.6		0.3
Issuance of common stock in connection with stock plans (in shares)	[1]		300,000
Issuance of common stock in connection with stock plans	[1]	0.0
Share-based compensation		7.5				7.5
Exercise of stock options (in shares)			300,000
Exercise of stock options		$ 5.1				5.1
Share repurchases (in shares)		130,900		100,000	[2]
Share repurchases	[2]	$ (3.3)		$ (3.3)
Other comprehensive income (loss)		(15.5)						(15.5)
Ending balance (in shares) at Sep. 30, 2019			73,000,000.0	300,000
Ending balance at Sep. 30, 2019		516.1	$ 0.7	$ (8.1)		52.2	604.5	(135.5)	2.3
Beginning balance (in shares) at Jun. 30, 2019			73,000,000.0	300,000
Beginning balance at Jun. 30, 2019		512.3	$ 0.7	$ (8.0)		50.2	587.9	(120.7)	2.2
Increase (Decrease) in Stockholders' Equity
Net income (loss)		16.7					16.6		0.1
Share-based compensation		1.9				1.9
Exercise of stock options		$ 0.1				0.1
Share repurchases (in shares)		5,200
Share repurchases		$ (0.1)		$ (0.1)
Other comprehensive income (loss)		(14.8)						(14.8)
Ending balance (in shares) at Sep. 30, 2019			73,000,000.0	300,000
Ending balance at Sep. 30, 2019		$ 516.1	$ 0.7	$ (8.1)		$ 52.2	$ 604.5	$ (135.5)	$ 2.3

[1] The par value of shares issued is not included in the table due to rounding.

[2] During the nine months ended September 30, 2019 and 2018, GCP withheld and retained approximately 131,000 shares and 45,000 shares, respectively, of Company common stock in a non-cash transaction with a cost of $3.3 million and $1.3 million, respectively, in connection with fulfilling statutory tax withholding requirements for employees under the provisions of the Company's equity compensation programs. During the nine months ended September 30, 2019 and 2018, cash payments for such tax withholding obligations were $3.3 million and $1.3 million, respectively.