Significant Accounting Policies (Narrative) (Details) (USD $)	0 Months Ended	12 Months Ended
	Sep. 07, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Significant Accounting Policies [Line Items]
PriorPeriodAdjustment			$ 24,100,000	$ 21,300,000
Stockholders' Equity Note, Stock Split, Conversion Ratio	1.5
Debt and Capital Lease Obligations		191,429,000	240,407,000
Depreciation expenses including capital leases		126,400,000	109,800,000	89,900,000
Other intangible assets		8,100,000	8,100,000
Accumulated amortization of intangible assets		6,400,000	5,700,000
Amortization expense		700,000	900,000	900,000
Self-insurance reserve		100,400,000	93,500,000
Long-term portions of self insurance reserve		61,600,000	59,500,000
Advertising expense		16,700,000	11,000,000	8,300,000
Company-owned life insurance contracts			6,800,000
Long-term Debt, Fair Value		196,500,000	247,900,000
Group Health Claims [Member]
Significant Accounting Policies [Line Items]
Insurance maximum, per occurrence		400,000
Self insurance additional coverage		400,000
Workers Compensation Claims [Member]
Significant Accounting Policies [Line Items]
Insurance maximum, per occurrence		1,000,000
Cargo Loss And Damage Claims [Member]
Significant Accounting Policies [Line Items]
Insurance maximum, per occurrence		100,000
Bodily Injury And Property Damage [Member]
Significant Accounting Policies [Line Items]
Insurance maximum, per occurrence		$ 2,750,000