Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Fair Value on Non-Recurring Basis
Amount of transfers of assets and liabilities measured on a recurring and non-recurring basis between Levels 1, 2 and 3 of the fair value hierarchy	$ 0	$ 0	$ 0	$ 0

Amount of transfers of assets and liabilities measured on a recurring and non-recurring basis between Levels 1, 2 and 3 of the fair value hierarchy.

No definition available.

Name:	bld_FairValueAssetsAndLiabilitiesLevel1Level2AndLevel3TransfersAmount
Namespace Prefix:	bld_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration