Investments in Affiliates Accounted for Using the Equity Method (Investment in Lending Tree) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Carrying amount	$ 167,643	$ 177,030
Share of earnings (losses) of affiliates	$ (2,629)	25,772	$ 7,001
LendingTree
Schedule of Equity Method Investments [Line Items]
Percentage ownership	26.50%
Market value	$ 1,045,044
Carrying amount	166,465	174,002
Share of earnings (losses) of affiliates	(1,600)	21,100	$ 7,000
Other
Schedule of Equity Method Investments [Line Items]
Carrying amount	$ 1,178	$ 3,028