MERGER WITH THE PPG CHEMICALS BUSINESS (Detail) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	12 Months Ended		0 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Jan. 28, 2013	Dec. 31, 2014
Unaudited pro forma information
Net sales	$ 4,773,700,000	$ 4,977,400,000
Net loss (income) attributable to Axiall	162,700,000	271,800,000
Earnings per share from net income attributable to Axiall - Basic (in dollars per share)	$ 2.33	$ 3.88
Earnings per share from net income attributable to Axiall - Diluted (in dollars per share)	$ 2.31	$ 3.87
Allocation of the purchase price to assets acquired and liabilities assumed
Goodwill	1,763,200,000			1,741,000,000
Additional disclosures
Estimated gain on acquisition of controlling interest	25,900,000
Merger inventory fair value acquisition accounting adjustment	13,400,000
Bridge loan
Additional disclosures
Financing fees associated with merger	11,000,000
Face amount of debt	688,000,000
Merged Business
Merger with the PPG chemical business
Purchase price			2,800,000,000
Number of shares of common stock issued for acquisition			35.2
Value of shares of common stock issued for acquisition			1,800,000,000
Debt assumed			967,000,000
Goodwill expected to be deductible for tax purposes			5,900,000
Allocation of the purchase price to assets acquired and liabilities assumed
Cash and cash equivalents	26,700,000		26,700,000
Receivables	234,300,000		236,700,000
Inventories	77,100,000		72,000,000
Prepaid expenses and other	7,600,000		11,900,000
Property, plant and equipment	926,900,000		957,300,000
Goodwill	1,572,700,000		1,454,300,000
Intangible assets	1,205,800,000		1,224,200,000
Other assets	42,200,000		42,500,000
Accounts payable	(96,600,000)		(97,800,000)
Income taxes payable	(4,700,000)		(4,700,000)
Accrued compensation	(20,600,000)		(20,600,000)
Other accrued taxes	(200,000)		(12,100,000)
Other accrued liabilities	(62,500,000)		(58,000,000)
Deferred income taxes	(681,400,000)		(614,900,000)
Pension and other postretirement benefits	(252,300,000)		(279,000,000)
Other non-current liabilities	(78,500,000)		(67,900,000)
Debt assumed	(967,000,000)		(967,000,000)
Noncontrolling interest	(130,000,000)		(130,300,000)
Total net assets acquired	1,799,500,000		1,773,300,000
Merged Business | Measurement Period Adjustments
Allocation of the purchase price to assets acquired and liabilities assumed
Receivables	(2,400,000)
Inventories	5,100,000
Prepaid expenses and other	(4,300,000)
Property, plant and equipment	(30,400,000)
Goodwill	118,400,000
Intangible assets	(18,400,000)
Other assets	(300,000)
Accounts payable	1,200,000
Other accrued taxes	11,900,000
Other accrued liabilities	(4,500,000)
Deferred income taxes	(66,500,000)
Pension and other postretirement benefits	26,700,000
Other non-current liabilities	(10,600,000)
Noncontrolling interest	300,000
Total net assets acquired	26,200,000
Merged Business | Impact of correction | Overstatement of certain assets and deferred tax liabilities
Allocation of the purchase price to assets acquired and liabilities assumed
Goodwill				700,000
Total net assets acquired				$ 700,000