Leases - Assets and Liabilities (Details) - USD ($) $ in Thousands	Jan. 31, 2021	Jul. 31, 2020
Leases [Abstract]
Operating lease right-of-use assets	$ 37,615	$ 33,609
Operating lease liabilities:
Other current liabilities	6,872	5,343
Other long-term liabilities	30,979	28,456
Total operating lease liabilities	37,851	33,799
Finance lease right-of-use assets	7,361	3,672
Finance lease liabilities
Other current liabilities	996	505
Other long-term liabilities	5,284	4,743
Total finance lease liabilities	$ 6,280	$ 5,248
Weighted-aver remaining lease term - operating leases	12 years 3 months 18 days	13 years 7 months 6 days
Weighted-aver remaining lease term - finance leases	5 years 6 months	6 years 9 months 18 days
Weighted-average discount rate - operating leases	3.30%	3.40%
Weighted-average discount rate - finance leases	8.80%	9.70%
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent	us-gaap:OtherLiabilitiesCurrent
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesNoncurrent
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	tho:PropertyPlantAndEquipmentAndFinanceAndOperatingLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	tho:PropertyPlantAndEquipmentAndFinanceAndOperatingLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	tho:PropertyPlantAndEquipmentAndFinanceAndOperatingLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization	tho:PropertyPlantAndEquipmentAndFinanceAndOperatingLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization