Net Investment Income and Net Realized and Unrealized Gains and Losses Table of Gains on Sale of Mortgage Loans and Equity Securities, Trading, Still Held (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Net realized gain on sale of mortgage loans (1)	[1]	$ 9,856	$ 16,476	$ 30,286	$ 47,237
Net unrealized gains (losses) on equity securities, at fair value held at the reporting date		$ (5,570)	$ (11,125)	$ (19,729)	$ (21,183)

[1] Related to the Company’s mortgage business.