Acquisition and Divestiture (Narrative) (Details) - USD ($) $ in Thousands		9 Months Ended
	Sep. 01, 2017	Sep. 30, 2017	Sep. 30, 2016	Aug. 14, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Cash payment to acquire business		$ 1,325,759	$ 25,394
Proceeds from issuance of Series A convertible preferred units, net		729,958	$ 0
6.500% Senior Unsecured Notes Due October 2025
Business Acquisition [Line Items]
Debt issued		$ 550,000			$ 0
Senior unsecured notes, stated rate		6.50%			6.50%
Class A Convertible Preferred Stock Units | Private Placement
Business Acquisition [Line Items]
Proceeds from issuance of convertible preferred stock, gross	$ 750,000
Alkali Business
Business Acquisition [Line Items]
Business Acquisition, Transaction Costs		$ 10,400
Cash payment to acquire business	1,325,000
Working capital included in cash payment to acquire business	$ 100,000
Average useful life of fixed assets acquired	15 years
Alkali Business | 6.500% Senior Unsecured Notes Due October 2025
Business Acquisition [Line Items]
Debt issued	$ 550,000			$ 550,000
Senior unsecured notes, stated rate	6.50%			6.50%
Proceeds from issuance of unsecured debt	$ 540,100
Alkali Business | Class A Convertible Preferred Stock Units | Private Placement
Business Acquisition [Line Items]
Proceeds from issuance of convertible preferred stock, gross	750,000
Proceeds from issuance of Series A convertible preferred units, net	$ 726,200