Consolidated Statements of Changes in Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Unrealized holding gains arising during period, taxes	$ 116	$ 16	$ 331
Realized net gains	61	302	47
Accretion of net unrealized losses transferred during the period, taxes	269	391	1,258
Pension liability adjustment, taxes	$ 2,263	$ 1,930	$ 286
Class A Common Stock [Member]
Conversion of Class B Common Stock to Class A Common Stock, shares	42,620,000	2,500,000	5,100,000
Cash dividends, per share	$ 0.48	$ 0.48	$ 0.48
Class B Common Stock [Member]
Conversion of Class B Common Stock to Class A Common Stock, shares	42,620,000	2,500,000	5,100,000
Cash dividends, per share	$ 0.24	$ 0.24	$ 0.24