Guarantor Information - Guarantor Condensed Consolidating Statement of Operations and Comprehensive Income (Loss) Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Condensed Income Statements, Captions [Line Items]
Net sales	$ 699.2	$ 784.6
Operating costs and expenses:
Cost of sales	619.0	680.7
Selling, general and administrative expenses	70.1	76.0
Restructuring and divestiture costs	36.7	0.7
Integration-related costs and other, net	3.4	5.1
Fees associated with unsolicited offer and strategic alternatives	5.2
Total operating costs and expenses	734.4	762.5
Operating income (loss)	(35.2)	22.1
Other expense:
Interest income (expense), net	(17.0)	(17.6)
Debt refinancing costs		(3.2)
Foreign currency exchange gain (loss)	(0.9)	(0.7)
Income (loss) from continuing operations before income taxes	(53.1)	0.6
Provision for (benefit from) income taxes	(22.8)	3.0
Income (loss) from continuing operations	(30.3)	(2.4)
Discontinued operations:
Loss from discontinued operations	(31.4)	(7.2)
Benefit from income taxes of discontinued operations	(8.4)	(0.8)
Net loss from discontinued operations	(23.0)	(6.4)
Consolidated net income (loss)	(53.3)	(8.8)
Less: net income attributable to noncontrolling interest	0.3	1.8
Net income (loss) attributable to Axiall	(53.6)	(10.6)
Comprehensive income (loss) attributable to Axiall	(31.7)	(38.4)
Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Net sales	(40.2)	(48.2)
Operating costs and expenses:
Cost of sales	(40.2)	(48.2)
Total operating costs and expenses	(40.2)	(48.2)
Other expense:
Equity in loss of subsidiaries	67.5	7.5
Income (loss) from continuing operations before income taxes	67.5	7.5
Income (loss) from continuing operations	67.5	7.5
Discontinued operations:
Consolidated net income (loss)	67.5	7.5
Net income (loss) attributable to Axiall	67.5	7.5
Comprehensive income (loss) attributable to Axiall	18.9	84.2
Parent Company [Member] | Reportable Legal Entities [Member]
Operating costs and expenses:
Selling, general and administrative expenses	12.9	12.4
Restructuring and divestiture costs	5.4	0.5
Integration-related costs and other, net	0.5	3.4
Fees associated with unsolicited offer and strategic alternatives	5.2
Total operating costs and expenses	24.0	16.3
Operating income (loss)	(24.0)	(16.3)
Other expense:
Interest income (expense), net	4.6	6.0
Foreign currency exchange gain (loss)		(0.1)
Equity in loss of subsidiaries	(45.0)	(3.0)
Income (loss) from continuing operations before income taxes	(64.4)	(13.4)
Provision for (benefit from) income taxes	(10.8)	(2.8)
Income (loss) from continuing operations	(53.6)	(10.6)
Discontinued operations:
Consolidated net income (loss)	(53.6)	(10.6)
Net income (loss) attributable to Axiall	(53.6)	(10.6)
Comprehensive income (loss) attributable to Axiall	(31.7)	(38.4)
Eagle Spinco Inc [Member] | Reportable Legal Entities [Member]
Other expense:
Interest income (expense), net	(19.8)	(20.9)
Debt refinancing costs		(0.1)
Foreign currency exchange gain (loss)		0.1
Equity in loss of subsidiaries	(10.3)	(7.0)
Income (loss) from continuing operations before income taxes	(30.1)	(27.9)
Provision for (benefit from) income taxes	(11.0)	(5.6)
Income (loss) from continuing operations	(19.1)	(22.3)
Discontinued operations:
Consolidated net income (loss)	(19.1)	(22.3)
Net income (loss) attributable to Axiall	(19.1)	(22.3)
Comprehensive income (loss) attributable to Axiall	(14.6)	(6.8)
Guarantor Subsidiaries Excluding Eagle Spinco Inc [Member] | Reportable Legal Entities [Member]
Condensed Income Statements, Captions [Line Items]
Net sales	627.2	712.7
Operating costs and expenses:
Cost of sales	567.6	626.3
Selling, general and administrative expenses	44.3	47.2
Restructuring and divestiture costs	9.5
Integration-related costs and other, net	2.9	1.1
Total operating costs and expenses	624.3	674.6
Operating income (loss)	2.9	38.1
Other expense:
Interest income (expense), net	(0.9)	(0.1)
Debt refinancing costs		(3.1)
Foreign currency exchange gain (loss)		(0.1)
Equity in loss of subsidiaries	(22.5)	(4.5)
Income (loss) from continuing operations before income taxes	(20.5)	30.3
Provision for (benefit from) income taxes	(2.1)	10.5
Income (loss) from continuing operations	(18.4)	19.8
Discontinued operations:
Loss from discontinued operations	(26.2)	(2.6)
Benefit from income taxes of discontinued operations	(8.4)	(0.8)
Net loss from discontinued operations	(17.8)	(1.8)
Consolidated net income (loss)	(36.2)	18.0
Net income (loss) attributable to Axiall	(36.2)	18.0
Comprehensive income (loss) attributable to Axiall	(14.3)	(11.9)
Guarantor Subsidiaries Including Eagle Spinco Inc [Member] | Reportable Legal Entities [Member]
Condensed Income Statements, Captions [Line Items]
Net sales	627.2	712.7
Operating costs and expenses:
Cost of sales	567.6	626.3
Selling, general and administrative expenses	44.3	47.2
Restructuring and divestiture costs	9.5
Integration-related costs and other, net	2.9	1.1
Total operating costs and expenses	624.3	674.6
Operating income (loss)	2.9	38.1
Other expense:
Interest income (expense), net	(20.7)	(20.9)
Debt refinancing costs		(3.2)
Foreign currency exchange gain (loss)		(0.1)
Equity in loss of subsidiaries	(22.5)	(4.5)
Income (loss) from continuing operations before income taxes	(40.3)	9.4
Provision for (benefit from) income taxes	(13.1)	4.9
Income (loss) from continuing operations	(27.2)	4.5
Discontinued operations:
Loss from discontinued operations	(26.2)	(2.6)
Benefit from income taxes of discontinued operations	(8.4)	(0.8)
Net loss from discontinued operations	(17.8)	(1.8)
Consolidated net income (loss)	(45.0)	2.7
Net income (loss) attributable to Axiall	(45.0)	2.7
Comprehensive income (loss) attributable to Axiall	(23.1)	(27.2)
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Income Statements, Captions [Line Items]
Net sales	112.2	120.1
Operating costs and expenses:
Cost of sales	91.6	102.6
Selling, general and administrative expenses	12.9	16.4
Restructuring and divestiture costs	21.8	0.2
Integration-related costs and other, net		0.6
Total operating costs and expenses	126.3	119.8
Operating income (loss)	(14.1)	0.3
Other expense:
Interest income (expense), net	(0.9)	(2.7)
Foreign currency exchange gain (loss)	(0.9)	(0.5)
Income (loss) from continuing operations before income taxes	(15.9)	(2.9)
Provision for (benefit from) income taxes	1.1	0.9
Income (loss) from continuing operations	(17.0)	(3.8)
Discontinued operations:
Loss from discontinued operations	(5.2)	(4.6)
Net loss from discontinued operations	(5.2)	(4.6)
Consolidated net income (loss)	(22.2)	(8.4)
Less: net income attributable to noncontrolling interest	0.3	1.8
Net income (loss) attributable to Axiall	(22.5)	(10.2)
Comprehensive income (loss) attributable to Axiall	$ 4.2	$ (57.0)