Derivative Financial Instruments and Hedging Activities Derivatives (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Nov. 30, 2017	Nov. 30, 2016	May 31, 2018	Aug. 31, 2017
Derivative [Line Items]
Derivative Asset, Noncurrent			$ 22,100	$ 186,900
Derivative Liability, Noncurrent			17,300	13,700
Derivative Asset, Fair Value, Amount Not Offset Against Collateral			466,068	380,236
Derivative Assets			505,861	418,952
Derivative Asset, Fair Value, Gross Amount Not Offset on Balance Sheet			39,793	38,716
Derivative Liability, Fair Value, Amount Not Offset Against Collateral			309,595	287,079
Derivative Liabilities			353,451	329,693
Derivative Liability, Collateral, Right to Reclaim Cash, Offset			4,063	3,898
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet			$ 39,793	38,716
Credit Rating Agencies Threshold, Minimum			66.67%
CF Nitrogen LLC [Member]
Derivative [Line Items]
Annual Payment Receivable Contingent On Investment Credit Rating			$ 5,000
Payments For Credit Rating Decrease In Investment	$ 5,000	$ 5,000
Embedded derivative asset			23,100
Embedded Derivative, Gain on Embedded Derivative		$ 24,100
Foreign currency derivatives | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral			3,484	5,135
Derivative Assets			9,298	8,771
Derivative Asset, Fair Value, Gross Amount Not Offset on Balance Sheet			5,814	3,636
Derivative Liability, Fair Value, Amount Not Offset Against Collateral			17,270	16,295
Derivative Liabilities			23,084	19,931
Derivative Liability, Collateral, Right to Reclaim Cash, Offset			0	0
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet			5,814	3,636
Derivative Asset, Notional Amount			934,500	776,700
Interest rate swap derivatives | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Liability, Fair Value, Amount Not Offset Against Collateral			3
Derivative Liabilities			3
Derivative Liability, Collateral, Right to Reclaim Cash, Offset			0
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet			0
Embedded Derivative Financial Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral			23,145	25,533
Derivative Assets			23,145	25,533
Derivative Asset, Fair Value, Gross Amount Not Offset on Balance Sheet			0	0
Commodity and freight derivatives | Not Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Amount Not Offset Against Collateral			439,439	349,568
Derivative Assets			473,418	384,648
Derivative Asset, Fair Value, Gross Amount Not Offset on Balance Sheet			33,979	35,080
Derivative Liability, Fair Value, Amount Not Offset Against Collateral			292,322	270,784
Derivative Liabilities			330,364	309,762
Derivative Liability, Collateral, Right to Reclaim Cash, Offset			4,063	3,898
Derivative Liability, Fair Value, Gross Amount Not Offset on Balance Sheet			33,979	$ 35,080
Fair Value Hedging [Member] | Interest rate swap derivatives | Designated as Hedging Instrument
Derivative [Line Items]
Derivative Asset, Notional Amount			$ 495,000