Income Taxes (Narrative) (Details) - USD ($)	3 Months Ended	6 Months Ended		12 Months Ended
	Dec. 31, 2017	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016
Income Tax Disclosure [Line Items]
Federal statutory corporate tax rate		21.00%		28.10%	34.00%	34.00%
Re-measurement of U.S. deferred tax assets and related valuation allowance				$ 0
Alternative minimum tax carryforward, recognition period				4 years
Alternative minimum tax repeal, benefit	$ 279,000
Transition tax rate, cash and cash equivalents				15.50%
Transition tax rate, other than cash and cash equivalents				8.00%
Transition tax payment period				8 years
Cash payments expected to make related to Transition Tax				$ 0
Tax credit carry-forwards		$ 7,475,000		$ 7,475,000	$ 5,284,000	$ 5,451,000
Cumulative loss period				3 years
Unrecognized tax benefits that would impact effective tax rate		73,000		$ 73,000	120,000
Accrued interest or penalties related to uncertain tax positions		0		$ 0
Earliest Tax Year [Member] | German Tax Authority [Member]
Income Tax Disclosure [Line Items]
Open tax year				2014
Earliest Tax Year [Member] | China Tax Authority [Member]
Income Tax Disclosure [Line Items]
Open tax year				2015
Latest Tax Year [Member] | German Tax Authority [Member]
Income Tax Disclosure [Line Items]
Open tax year				2018
Latest Tax Year [Member] | China Tax Authority [Member]
Income Tax Disclosure [Line Items]
Open tax year				2018
Internal Revenue Service (IRS) [Member]
Income Tax Disclosure [Line Items]
Operating loss carryfoward related to exercise of employee stock options		8,300,000		$ 8,300,000
Increase (decrease) in valuation allowance				(1,254,000)	$ (354,000)	$ 16,349,000
Internal Revenue Service (IRS) [Member] | Tax Years 2022 Through 2036 [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforward		25,800,000		25,800,000
Internal Revenue Service (IRS) [Member] | Tax Years 2019 Through 2036 [Member]
Income Tax Disclosure [Line Items]
Tax credit carry-forwards		$ 5,000,000		$ 5,000,000
Internal Revenue Service (IRS) [Member] | Earliest Tax Year [Member]
Income Tax Disclosure [Line Items]
Open tax year				2015
Internal Revenue Service (IRS) [Member] | Latest Tax Year [Member]
Income Tax Disclosure [Line Items]
Open tax year				2018
Maximum [Member]
Income Tax Disclosure [Line Items]
Federal statutory corporate tax rate			35.00%
Maximum [Member] | Internal Revenue Service (IRS) [Member] | Tax Years 2022 Through 2036 [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforward, expiration date				Dec. 31, 2036
Maximum [Member] | Internal Revenue Service (IRS) [Member] | Tax Years 2019 Through 2036 [Member]
Income Tax Disclosure [Line Items]
Tax credit carryforward, expiration date				Jun. 30, 2036
Minimum [Member] | Internal Revenue Service (IRS) [Member] | Tax Years 2022 Through 2036 [Member]
Income Tax Disclosure [Line Items]
Operating loss carryforward, expiration date				Jun. 30, 2022
Minimum [Member] | Internal Revenue Service (IRS) [Member] | Tax Years 2019 Through 2036 [Member]
Income Tax Disclosure [Line Items]
Tax credit carryforward, expiration date				Jan. 01, 2019