Consolidated Statement of Changes in Shareholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common stock [Member]	Retained earnings [Member]	Retained earnings [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Accumulated other comprehensive income (loss), net of tax [Member]	Treasury stock, at cost [Member]	Common shares outstanding [Member]
Shareholders' Equity [Roll Forward]
Shareholders' equity		$ 23,144,000	$ 35,204,000		$ (1,859,000)	$ (33,595,000)
Balance, beginning of year at Dec. 31, 2018		23,144,000	35,204,000		(1,859,000)	(33,595,000)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		173,000
Compensation amortization under share-based plans and other changes		115,000
Shareholders' equity	$ 25,607,000	23,432,000	36,317,000		625,000	(34,767,000)
Net income	1,749,000		1,749,000
Dividends			(636,000)
Other			0
Other comprehensive income	2,484,000				2,484,000
Treasury stock acquired — share repurchase authorization						(1,125,000)
Net shares acquired related to employee share-based compensation plans						(47,000)
Balance, end of period at Sep. 30, 2019	25,607,000	23,432,000	36,317,000		625,000	(34,767,000)
Balance, beginning of year (in shares) at Dec. 31, 2018							263,600,000
Common shares outstanding
Treasury stock acquired - share repurchase authorization (in shares)							(8,000,000.0)
Net shares issued under employee share-based compensation plans (in shares)							2,500,000
Balance, end of period (in shares) at Sep. 30, 2019							258,100,000
Shareholders' Equity [Roll Forward]
Shareholders' equity		23,372,000	36,135,000		206,000	(34,392,000)
Balance, beginning of year at Jun. 30, 2019		23,372,000	36,135,000		206,000	(34,392,000)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		28,000
Compensation amortization under share-based plans and other changes		32,000
Shareholders' equity	25,607,000	23,432,000	36,317,000		625,000	(34,767,000)
Net income	396,000		396,000
Dividends			(215,000)
Other			1,000
Other comprehensive income	419,000				419,000
Treasury stock acquired — share repurchase authorization						(375,000)
Net shares acquired related to employee share-based compensation plans						0
Balance, end of period at Sep. 30, 2019	25,607,000	23,432,000	36,317,000		625,000	(34,767,000)
Balance, beginning of year (in shares) at Jun. 30, 2019							260,300,000
Common shares outstanding
Treasury stock acquired - share repurchase authorization (in shares)							(2,500,000)
Net shares issued under employee share-based compensation plans (in shares)							300,000
Balance, end of period (in shares) at Sep. 30, 2019							258,100,000
Shareholders' Equity [Roll Forward]
Shareholders' equity	25,607,000	23,432,000	36,317,000		625,000	(34,767,000)
Shareholders' equity	25,943,000	23,469,000	36,977,000	$ (43,000)	640,000	(35,143,000)
Balance, beginning of year at Dec. 31, 2019	25,943,000	23,469,000	36,977,000	(43,000)	640,000	(35,143,000)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		64,000
Compensation amortization under share-based plans and other changes		113,000
Shareholders' equity	$ 27,849,000	23,646,000	37,679,000	$ (43,000)	2,138,000	(35,614,000)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member
Net income	$ 1,387,000		1,387,000
Dividends			(646,000)
Other			4,000
Other comprehensive income	1,498,000				1,498,000
Treasury stock acquired — share repurchase authorization	(425,000)					(425,000)
Net shares acquired related to employee share-based compensation plans	(46,000)					(46,000)
Balance, end of period at Sep. 30, 2020	$ 27,849,000	23,646,000	37,679,000		2,138,000	(35,614,000)
Balance, beginning of year (in shares) at Dec. 31, 2019	255,500,000						255,500,000
Common shares outstanding
Treasury stock acquired - share repurchase authorization (in shares)	(3,500,000)						(3,500,000)
Net shares issued under employee share-based compensation plans (in shares)							1,300,000
Balance, end of period (in shares) at Sep. 30, 2020	253,300,000						253,300,000
Shareholders' Equity [Roll Forward]
Shareholders' equity		23,606,000	37,069,000		1,882,000	(35,614,000)
Balance, beginning of year at Jun. 30, 2020		23,606,000	37,069,000		1,882,000	(35,614,000)
Shareholders' Equity [Roll Forward]
Employee share-based compensation		8,000
Compensation amortization under share-based plans and other changes		32,000
Shareholders' equity	$ 27,849,000	23,646,000	37,679,000		2,138,000	(35,614,000)
Net income	827,000		827,000
Dividends			(218,000)
Other			1,000
Other comprehensive income	256,000				256,000
Treasury stock acquired — share repurchase authorization						0
Net shares acquired related to employee share-based compensation plans	(159)					0
Balance, end of period at Sep. 30, 2020	$ 27,849,000	23,646,000	37,679,000		2,138,000	(35,614,000)
Balance, beginning of year (in shares) at Jun. 30, 2020							253,200,000
Common shares outstanding
Treasury stock acquired - share repurchase authorization (in shares)	0						0
Net shares issued under employee share-based compensation plans (in shares)							100,000
Balance, end of period (in shares) at Sep. 30, 2020	253,300,000						253,300,000
Shareholders' Equity [Roll Forward]
Shareholders' equity	$ 27,849,000	$ 23,646,000	$ 37,679,000		$ 2,138,000	$ (35,614,000)