Other Long-Term Assets Components of Other Long-Term Assets (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Convertible 2022 note hedge asset	$ 0	$ 2,062,000
Convertible 2021 note hedge asset	0	1,028,000
Cash surrender value of life insurance policies	1,998,000	1,948,000
Deferred financing fees	208,000	402,000
Long-term installment receivables	547,000	222,000
Long-term deferred taxes	580,000	352,000
Investments	86,000	90,000
Other	250,000	256,000
Other Long-Term Assets	$ 3,669,000	$ 6,360,000