Investment Securities Debt Securities, Available-for-Sale - Sales (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019		Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Amortized cost of debt securities sold	[1]	$ 5,680	$ 11,621		$ 122,652
Gross realized gains on sales		227	149	[2]	25
Gross realized losses on sales		0	(3)		(2,975)
Total proceeds from sales of debt securities		$ 5,907	$ 11,767		$ 119,702

[1] Amortized cost of investments sold is determined on a specific identification basis and includes pending trades based on trade date, if applicable.

[2] Immaterial amount of capital gain distributions realized from mutual funds included in 2018.