Investments in Affiliates Accounted for Using the Equity Method (Investment in Lending Tree) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Carrying amount	$ 157,484		$ 157,484		$ 167,643
Share of earnings (loss) of affiliates, net	$ (9,035)	$ 1,921	$ (7,504)	$ (2,443)
LendingTree
Schedule of Equity Method Investments [Line Items]
Percentage ownership	26.30%		26.30%
Market value	$ 1,056,926		$ 1,056,926
Carrying amount	156,627		156,627		166,465
Share of earnings (loss) of affiliates, net	(9,100)	$ 2,000	(7,300)	$ (1,400)
Other
Schedule of Equity Method Investments [Line Items]
Carrying amount	$ 857		$ 857		$ 1,178