Consolidated Statement of Stockholders' Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Stockholders' Equity Attributable to Thor	Stockholders' Equity Attributable to Thor Cumulative Effect, Period of Adoption, Adjustment	Non-controlling Interests
Balance (in shares) at Jul. 31, 2017			62,597,110					10,011,069
Balance at beginning of period at Jul. 31, 2017	$ 1,576,540		$ 6,260	$ 235,525	$ 1,670,826			$ (336,071)	$ 1,576,540
Net income (loss)	430,151				430,151				430,151
Restricted stock unit activity (in shares)			168,714					59,390
Restricted stock unit activity	(7,961)		$ 17	(321)				$ (7,657)	(7,961)
Cash dividends paid	(77,989)
Cash dividends	(77,989)								(77,989)
Stock compensation expense	17,000			17,000					17,000
Balance (in shares) at Jul. 31, 2018			62,765,824					10,070,459
Balance at end of period at Jul. 31, 2018	1,937,741		$ 6,277	252,204	2,022,988			$ (343,728)	1,937,741
Cumulative effect of adoption of ASU no. 2014-09, net of tax		$ (5,450)				$ (5,450)				$ (5,450)
Net income (loss)	132,465				133,275				133,275
Restricted stock unit activity (in shares)			167,591					55,975
Restricted stock unit activity	(3,116)		$ 16	1,286				$ (4,418)	(3,116)
Cash dividends paid	(84,139)
Cash dividends	(84,139)								(84,139)
Stock compensation expense	18,950			18,950					18,950
Other comprehensive income (loss)	(57,598)						$ (57,004)		(57,004)		$ (594)
Acquisitions (in shares)			2,256,492
Acquisitions	156,375		$ 226	143,942					144,168		12,207
Balance (in shares) at Jul. 31, 2019			65,189,907					10,126,434
Balance at end of period at Jul. 31, 2019	$ 2,095,228		$ 6,519	416,382	2,066,674		(57,004)	$ (348,146)	2,084,425		10,803
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201409Member
Cumulative effect of adoption of ASU no. 2014-09, net of tax	$ 2,084,425
Net income (loss)	221,384				222,974				222,974
Restricted stock unit activity (in shares)			206,624					71,341
Restricted stock unit activity	(3,185)		$ 21	557				$ (3,763)	(3,185)
Cash dividends paid	(88,318)
Cash dividends	(88,318)								(88,318)
Stock compensation expense	19,889			19,889					19,889
Other comprehensive income (loss)	83,736						83,997		83,997		(261)
Acquisitions	16,835										16,835
Balance (in shares) at Jul. 31, 2020			65,396,531					10,197,775
Balance at end of period at Jul. 31, 2020	2,345,569		$ 6,540	$ 436,828	$ 2,201,330		$ 26,993	$ (351,909)	$ 2,319,782		$ 25,787
Cumulative effect of adoption of ASU no. 2014-09, net of tax	$ 2,319,782