Income Taxes - Additional Information (Details) - USD ($)		3 Months Ended			9 Months Ended		12 Months Ended
	Jan. 01, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2018	Dec. 31, 2017
Income Taxes [Line Items]
United States statutory tax rate	21.00%	24.50%		35.00%	24.50%	35.00%		35.00%
Valuation allowance for deferred tax assets or provision for income taxes		$ 0			$ 0
Company's effective tax rates		(1.10%)		(4.70%)	3.10%	(3.90%)
Amended prior year tax return, refund claim amount			$ 700,000
Scenario, Plan
Income Taxes [Line Items]
United States statutory tax rate							24.50%