General and Summary of Significant Accounting Policies Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Equity Securities, Amortized Cost Basis	$ 39,354	$ 24,640
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Tax	0	0
Available-for-sale Securities	$ 39,354	24,640
Investment Contract Settlement Date Range End	Jul. 22, 2020
Investment Contract Settlement Date Range Start	Jan. 09, 2019
Long-term Investments [Domain]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Equity Securities, Amortized Cost Basis	$ 2,025	14,579
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Tax	0	0
Available-for-sale Securities	2,025	14,579
Short-term Investments [Member]
Debt Securities, Available-for-sale [Line Items]
Available-for-sale Equity Securities, Amortized Cost Basis	37,329	10,061
Other Comprehensive Income (Loss), Securities, Available-for-sale, Adjustment, before Tax	0	0
Available-for-sale Securities	$ 37,329	$ 10,061