Income Taxes (Provision for Income Taxes Differed from Amounts Computed by the U.S. Federal Income Tax Rate) (Details) - USD ($)	5 Months Ended	7 Months Ended	12 Months Ended
	Dec. 31, 2017	Jul. 31, 2018	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Computed expected tax expense (benefit)			$ 6,615,000	$ 8,919,000	$ (2,867,000)
State and local income taxes, net of federal benefit			1,193,000	1,257,000	23,000
Stock-based compensation			(1,112,000)	78,000	68,000
Research and experimentation credits			(678,000)	(919,000)	(1,106,000)
Acquisition-related tax contingencies			0	0	1,962,000
Nondeductible transaction costs			0	0	1,279,000
Tax Reform remeasurement of deferred taxes			(11,317,000)	0	0
Foreign income taxes			(221,000)	(151,000)	289,000
Other			377,000	470,000	(102,000)
(Benefit from) provision for income taxes			$ (5,143,000)	$ 9,654,000	$ (454,000)
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Computed expected tax expense (benefit)	35.00%	21.00%	27.00%	35.00%	35.00%
State and local income taxes, net of federal benefit			4.80%	4.90%	(0.30%)
Stock-based compensation			(4.50%)	0.30%	(0.80%)
Research and experimentation credits			(2.80%)	(3.60%)	13.50%
Acquisition-related tax contingencies			0.00%	0.00%	(24.00%)
Nondeductible transaction costs			0.00%	0.00%	(15.60%)
Tax Reform remeasurement of deferred taxes			(46.00%)	0.00%	0.00%
Foreign income taxes			(0.90%)	(0.60%)	(3.50%)
Other			1.40%	1.90%	1.20%
(Benefit from) provision for income taxes			(21.00%)	37.90%	5.50%