Equities - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Aug. 31, 2018	May 31, 2018	Feb. 28, 2018	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Feb. 28, 2018	Feb. 28, 2017	May 31, 2018	May 31, 2017	Aug. 31, 2018	Aug. 31, 2017	Aug. 31, 2016
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	$ 7,920,836	$ 7,866,357	$ 7,742,948	$ 7,705,640	$ 7,680,371	$ 7,808,580	$ 7,819,516	$ 7,759,159	$ 7,705,640	$ 7,759,159	$ 7,705,640	$ 7,759,159	$ 7,705,640	$ 7,759,159	$ 7,551,439
Other comprehensive income (loss), net of tax	(5,621)	(72)	10,111	3,019	28,208	2,524	13,843	(13,405)	13,130	438	13,058	2,962	7,437	31,170	1,307
Reclassification of tax effects to retained earnings													0
Balance	8,165,028	7,920,836	7,866,357	7,742,948	7,705,640	7,680,371	7,808,580	7,819,516	7,866,357	7,808,580	7,920,836	7,680,371	8,165,028	7,705,640	7,759,159
Pension and Other Postretirement Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance				(132,444)				(165,146)	(132,444)	(165,146)	(132,444)	(165,146)	(132,444)	(165,146)	(171,729)
Amounts before reclassifications													7,633	25,216	(10,512)
Amounts reclassified out													21,804	26,174	20,998
Total other comprehensive income (loss), before tax													29,437	51,390	10,486
Tax effect													(9,371)	(18,688)	(3,903)
Other comprehensive income (loss), net of tax													20,066	32,702	6,583
Reclassification of tax effects to retained earnings													(27,957)
Balance	(140,335)				(132,444)								(140,335)	(132,444)	(165,146)
Unrealized Net Gain (Loss) on Available for Sale Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance				10,041				5,656	10,041	5,656	10,041	5,656	10,041	5,656	4,156
Amounts before reclassifications													21,078	7,117	2,447
Amounts reclassified out													(25,534)	0	0
Total other comprehensive income (loss), before tax													(4,456)	7,117	2,447
Tax effect													1,308	(2,732)	(947)
Other comprehensive income (loss), net of tax													(3,148)	4,385	1,500
Reclassification of tax effects to retained earnings													1,968
Balance	8,861				10,041								8,861	10,041	5,656
Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance				(6,954)				(9,196)	(6,954)	(9,196)	(6,954)	(9,196)	(6,954)	(9,196)	(5,324)
Amounts before reclassifications													1,031	1,892	(11,353)
Amounts reclassified out													1,704	1,742	5,071
Total other comprehensive income (loss), before tax													2,735	3,634	(6,282)
Tax effect													(195)	(1,392)	2,410
Other comprehensive income (loss), net of tax													2,540	2,242	(3,872)
Reclassification of tax effects to retained earnings													(1,468)
Balance	(5,882)				(6,954)								(5,882)	(6,954)	(9,196)
Foreign Currency Translation Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance				(51,003)				(42,844)	(51,003)	(42,844)	(51,003)	(42,844)	(51,003)	(42,844)	(39,940)
Amounts before reclassifications													(10,062)	(7,960)	(2,210)
Amounts reclassified out													(2,042)	15	469
Total other comprehensive income (loss), before tax													(12,104)	(7,945)	(1,741)
Tax effect													83	(214)	(1,163)
Other comprehensive income (loss), net of tax													(12,021)	(8,159)	(2,904)
Reclassification of tax effects to retained earnings													465
Balance	(62,559)				(51,003)								(62,559)	(51,003)	(42,844)
Accumulated Other Comprehensive Loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance				(180,360)				(211,530)	(180,360)	(211,530)	(180,360)	(211,530)	(180,360)	(211,530)	(212,837)
Amounts before reclassifications													19,680	26,265	(21,628)
Amounts reclassified out													(4,068)	27,931	26,538
Total other comprehensive income (loss), before tax													15,612	54,196	4,910
Tax effect													(8,175)	(23,026)	(3,603)
Other comprehensive income (loss), net of tax													7,437	31,170	1,307
Reclassification of tax effects to retained earnings	(27,000)												(26,992)
Balance	(199,915)				(180,360)								(199,915)	(180,360)	(211,530)
As Previously Reported
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	8,162,533	8,061,960	7,937,775	7,905,825	7,858,956	7,961,594	7,931,280	7,866,250	7,905,825	7,866,250	7,905,825	7,866,250	7,905,825	7,866,250	7,669,411
Other comprehensive income (loss), net of tax		(1,501)	10,219	5,225	26,030	1,742	14,778	(14,494)	15,445	284	13,944	2,026		28,056	2,481
Balance		8,162,533	8,061,960	7,937,775	7,905,825	7,858,956	7,961,594	7,931,280	8,061,960	7,961,594	8,162,533	7,858,956		7,905,825	7,866,250
As Previously Reported | Pension and Other Postretirement Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance															(171,729)
As Previously Reported | Unrealized Net Gain (Loss) on Available for Sale Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance															4,156
As Previously Reported | Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance															(5,324)
As Previously Reported | Foreign Currency Translation Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance															(41,310)
As Previously Reported | Accumulated Other Comprehensive Loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance				(183,670)				(211,726)	(183,670)	(211,726)	(183,670)	(211,726)	(183,670)	(211,726)	(214,207)
Balance					(183,670)									(183,670)	(211,726)
Restatement Adjustments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance	$ (241,697)	(195,603)	(194,827)	(200,185)	(178,585)	(153,014)	(111,764)	(107,091)	(200,185)	(107,091)	(200,185)	(107,091)	(200,185)	(107,091)	(117,972)
Other comprehensive income (loss), net of tax		1,429	(108)	(2,206)	2,178	782	(935)	1,089	(2,315)	154	(886)	936		3,114	(1,174)
Balance		$ (241,697)	$ (195,603)	(194,827)	(200,185)	$ (178,585)	$ (153,014)	(111,764)	(195,603)	(153,014)	(241,697)	(178,585)		(200,185)	(107,091)
Restatement Adjustments | Pension and Other Postretirement Benefits
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance															0
Restatement Adjustments | Unrealized Net Gain (Loss) on Available for Sale Investments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance															0
Restatement Adjustments | Cash Flow Hedges
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance															0
Restatement Adjustments | Foreign Currency Translation Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance															1,370
Restatement Adjustments | Accumulated Other Comprehensive Loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance				$ 3,310				$ 196	$ 3,310	$ 196	$ 3,310	$ 196	$ 3,310	196	1,370
Balance					$ 3,310									$ 3,310	$ 196