Fair Value Measurements and Financial Instruments Fair Value Measurements (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Defined benefit pension plan assets	$ 3,758	$ 7,105	$ 11,509
Revolving credit facility, noncurrent	93,500	100,000
Total	155,563	117,351
Quoted prices in active markets, (level 1) [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Defined benefit pension plan assets	0	6,208
Significant other observable inputs, (level 2) [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Defined benefit pension plan assets	3,758	897
Significant unobservable inputs (level 3) [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Defined benefit pension plan assets	0	0
Fair value measurements, recurring [Member] | Quoted prices in active markets, (level 1) [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Assets invested for self-insurance, classified as other assets, noncurrent	15,379	19,422
Defined benefit pension plan assets	0	6,208
Deferred compensation	0	0
Fair value measurements, recurring [Member] | Significant other observable inputs, (level 2) [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Assets invested for self-insurance, classified as other assets, noncurrent	0	0
Defined benefit pension plan assets	3,758	897
Deferred compensation	2,459	2,146
Fair value measurements, recurring [Member] | Significant unobservable inputs (level 3) [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Assets invested for self-insurance, classified as other assets, noncurrent	0	0
Defined benefit pension plan assets	0	0
Deferred compensation	0	0
Fair value [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Revolving credit facility, noncurrent	93,500	100,000
Senior unsecured notes	56,002	12,389
Term loans, noncurrent	6,868	10,038
Total	156,370	122,427
Total carrying value [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Revolving credit facility, noncurrent	93,500	100,000
Senior unsecured notes	56,000	12,000
Term loans, noncurrent	6,662	7,935
Total	156,162	119,935
Total carrying value [Member] | Fair value measurements, recurring [Member]
Fair value, assets and liabilities measured on recurring and nonrecurring basis [Line Items]
Assets invested for self-insurance, classified as other assets, noncurrent	15,379	19,422
Defined benefit pension plan assets	3,758	7,105
Deferred compensation	$ 2,459	$ 2,146