Investments - Equity Securities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Investments
Investments - equity securities	$ 36,132
Unrealized gains on investments - equity securities	(3,035)
Reclassification into retained earnings	$ 932	[1]

[1] The reclassification into retained earnings relates to the adoption of ASU 2016-01. The new guidance was effective January 1, 2018, and required equity investments to be measured at fair value with changes in fair value recognized in results of operations rather than the consolidated statements of comprehensive income. See Note 2. Summary of Significant Accounting Policies.