Significant Accounting Policies (Narrative) (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Significant Accounting Policies [Line Items]
Stock Repurchase Program, Authorized Amount	$ 200,000,000
Debt and Capital Lease Obligations	155,714,000us-gaap_DebtAndCapitalLeaseObligations	191,429,000us-gaap_DebtAndCapitalLeaseObligations
Depreciation expenses including capital leases	145,800,000us-gaap_Depreciation	126,400,000us-gaap_Depreciation	109,800,000us-gaap_Depreciation
Self-insurance reserve	107,700,000us-gaap_SelfInsuranceReserve	100,400,000us-gaap_SelfInsuranceReserve
Long-term portions of self insurance reserve	65,400,000us-gaap_SelfInsuranceReserveNoncurrent	61,600,000us-gaap_SelfInsuranceReserveNoncurrent
Advertising expense	19,300,000us-gaap_AdvertisingExpense	16,700,000us-gaap_AdvertisingExpense	11,000,000us-gaap_AdvertisingExpense
Long-term Debt, Fair Value	165,500,000us-gaap_LongTermDebtFairValue	202,200,000us-gaap_LongTermDebtFairValue
Stock Repurchased During Period, Shares	70,620
Stock Repurchased and Retired During Period, Value	5,532,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount	194,500,000
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

Insurance Maximum, Per Occurrence

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- Definition

Additional self insurance coverage in excess of the retention level.

+ References

No definition available.

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- Details

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- Definition

Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 720

-SubTopic 35

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6420018&loc=d3e36677-107848

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- Definition

Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

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-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.13,16)

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- Definition

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

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- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

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- Definition

Carrying amount (including both current and noncurrent portions) of accrued known and estimated losses incurred as of the balance sheet date for which no insurance coverage exists, and for which a claim has been made or is probable of being asserted, typically arising from workmen's compensation-type of incidents and personal injury to nonemployees from accidents on the entity's property.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.24)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Carrying amount of accrued known and estimated losses incurred as of the balance sheet date for which no insurance coverage exists, and for which a claim has been made or is probable of being asserted, typically arising from workmen's compensation-type of incidents and personal injury to nonemployees from accidents on the entity's property that are expected to be paid after one year (or the normal operating cycle, if longer).

+ References

No definition available.

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- Definition

Number of shares that have been repurchased and retired during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

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- Definition

Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

+ References

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- Definition

Amount of stock repurchase plan authorized.

+ References

No definition available.

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- Definition

Amount remaining of a stock repurchase plan authorized.

+ References

No definition available.

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