Short and Long-Term Debt and Commitments Related to Letters of Credit (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Schedule of short-term debt [Table Text Block]

Short-term debt consisted of the following:

	December 31,
	2018		2017
Notes payable	$	—	$	149
Current portion of long-term debt	22,514		16,166
	$	22,514	$	16,315

Schedule of long-term debt instruments [Table Text Block]

Long-term debt consisted of the following:

	December 31,
	2018		2017
Revolving credit facility
Swing-line borrowings	$	2,500	$	—
LIBOR borrowings	91,000		100,000
	93,500		100,000
5.09% Senior unsecured notes	12,000		18,000
3.99% Senior unsecured notes	50,000		—
Term loans	23,176		16,242
	178,676		134,242
Less debt issuance costs	599		725
Less current portion	22,514		16,166
	$	155,563	$	117,351