Retirement Plans, Pension Plan Assets (Details) - Pension Plan [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	$ 28,299	$ 31,768	$ 36,141
Level 1 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	6,543	7,204
Level 2 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	21,756	24,564
Level 3 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	0	0
Domestic [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	5,385	6,226
Domestic [Member] | Level 1 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	5,385	6,226
Domestic [Member] | Level 2 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	0	0
Domestic [Member] | Level 3 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	0	0
International [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	83	101
International [Member] | Level 1 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	0	0
International [Member] | Level 2 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	83	101
International [Member] | Level 3 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	0	0
International Fixed Income Funds [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	22,703	25,340
International Fixed Income Funds [Member] | Level 1 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	1,111	934
International Fixed Income Funds [Member] | Level 2 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	21,592	24,406
International Fixed Income Funds [Member] | Level 3 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	0	0
Other Investments [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	128	101
Other Investments [Member] | Level 1 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	47	44
Other Investments [Member] | Level 2 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	81	57
Other Investments [Member] | Level 3 [Member]
Pension Plan Assets by Asset Category [Abstract]
Total assets at fair value	$ 0	$ 0