Long-Term Investments (Investments) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) investment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities at fair value that qualify for the NAV practical expedient	$ 45,781	$ 54,628
Equity-method investments	15,942	11,631
Long-term investments	61,723	66,259
Proceeds from long-term equity method investment	17,875	7,007	$ 1,239
Proceeds from sale or liquidation of long-term investments	$ 8,256	$ 19,487	$ 966
NAV
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of investments redeemed that qualify for the NAV practical expedient | investment	2
Percent of other investments redeemed that qualify for the NAV practical expedient	100.00%
Proceeds from long-term equity method investment	$ 8,320
In-transit redemptions	8,502
Gain on redemptions	$ 1,796