Acquisition (Allocation of Purchase Consideration) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	Aug. 31, 2016	Aug. 30, 2016	Sep. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill			$ 1,011,342	$ 946,553
Axiall Corporation [Member]
Business Acquisition [Line Items]
Goodwill	$ 942,096
Offer per share (in dollars per share)	$ 33.00
Multiplied by number of shares outstanding at acquisition	67,277
Fair value of Axiall shares outstanding purchased by the Company	$ 2,220,141
Axiall debt repaid at acquisition	247,135
Seller's transaction costs paid by the Company	47,458
Total fair value of consideration transferred	2,514,734
Fair value of Axiall share-based awards attributed to pre-combination service	11,346
Additional settlement value of shares acquired	13,280
Purchase consideration	2,539,360
Fair value of previously held equity interest in Axiall	102,300
Total fair value allocated to net assets acquired	2,641,660
Equity interest in acquiree held prior to combination, shares		3,100
Step acquisition, equity interest in acquiree, remeasurement gain (loss), net	$ 49,080