Effective Tax Rate Reconciliation (Details)	12 Months Ended
	Jun. 30, 2018 Rate	Dec. 31, 2017 Rate	Jun. 30, 2017 Rate	Jun. 30, 2016 Rate
Income Tax Disclosure [Abstract]
Computed expected tax expense	28.10%	35.00%	35.00%	35.00%
State income taxes, net of federal income tax benefits	2.90%		2.60%	1.90%
Research and development credit	(1.80%)		(2.00%)	(2.50%)
Domestic production activities deduction	(1.20%)		(2.10%)	(1.90%)
Sale of subsidiary stock	0.00%		0.00%	(1.70%)
Deferred tax adjustments resulting from Tax Cuts and Jobs Act, rate reconciliation	(24.20%)		(0.00%)	(0.00%)
Tax effects of share-based payments	(0.80%)		(0.70%)	(0.00%)
Other reconciling items (net)	0.70%		0.20%	0.20%
Effective Income Tax Rate Continuing Operations, percent	3.70%		33.00%	31.00%