Investment Securities Summary of Gains and Losses from Equity and Debt Securities, and Losses from Other-than-Temporary Impairment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity Securities, FV-NI, Realized Gain	$ 9	$ 13,558	$ 2,005
Debt and Equity Securities, Realized Gain (Loss)	37	9,071	2,550
Debt Securities, Available-for-sale, Realized Gain (Loss)	28	(4,487)	555
Debt And Equity Securities, Realized Gain	1,665	13,873	2,586
Equity Securities, FV-NI, Realized Gain (Loss)	9	13,558	1,995
Debt Securities, Available-for-sale, Realized Gain	1,656	315	581
Equity Securities, FV-NI, Realized Loss	0	0	10
Debt Securities, Available-for-sale, Realized Loss	1,628	4,802	26
Debt And Equity Securities, Realized Loss	$ 1,628	$ 4,802	$ 36