Investments Fair Value Inputs, Assets, Quantitative Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Equity Securities without Readily Determinable Fair Value
Other investments, cost	$ 960,711
Fair value	8,213
Limited Partner
Equity Securities without Readily Determinable Fair Value
Other investments, cost	7,988	$ 7,757
Unrealized gain	225	324
Fair value	8,213	8,081
Unrealized loss	0	0
Certificates of Deposit
Equity Securities without Readily Determinable Fair Value
Certificates of Deposit, at Carrying Value	300	300
Other investments, cost	300	300
Unrealized gain	0	0
Unrealized loss	0	0
Other Long-term Investments
Equity Securities without Readily Determinable Fair Value
Other investments, cost	8,288	8,057
Unrealized gain	225	324
Unrealized loss	0	0
Total other investments	$ 8,513	$ 8,381