LONG-TERM DEBT AND FINANCING ARRANGEMENTS (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Long-term debt obligations
Long-term debt	$ 127,730	$ 112,845
Less current portion	25,256	31,513
Long-term debt, less current portion	102,474	81,332
Weighted-average interest rate (as a percent)	1.70%us-gaap_DebtWeightedAverageInterestRate
Payments under long-term debt obligations
Due in one year or less	27,300
Due after one year through two years	20,899
Due after two years through three years	15,699
Due after three years through four years	2,607
Due after four years through five years	2,732
Due after five years	70,019
Total payments	139,256
Less amounts representing interest	11,526
Long-term debt	127,730	112,845
Term Loan
Long-term debt obligations
Long-term debt	70,000	83,750
Interest rate (as a percent)	1.40%
Payments under long-term debt obligations
Long-term debt	70,000	83,750
Credit Facility
Long-term debt obligations
Long-term debt	70,000
Payments under long-term debt obligations
Due in one year or less	1,124
Due after one year through two years	1,727
Due after two years through three years	2,223
Due after three years through four years	2,381
Due after four years through five years	2,500
Due after five years	70,000
Total payments	79,955
Less amounts representing interest	9,955
Long-term debt	70,000
Notes payable
Long-term debt obligations
Long-term debt	56,759	22,082
Weighted-average interest rate (as a percent)	2.00%
Payments under long-term debt obligations
Long-term debt	56,759	22,082
Notes payable \| Revenue equipment
Long-term debt obligations
Long-term debt	56,759
Payments under long-term debt obligations
Due in one year or less	25,959
Due after one year through two years	18,959
Due after two years through three years	13,257
Total payments	58,175
Less amounts representing interest	1,416
Long-term debt	56,759
Capital lease obligations
Long-term debt obligations
Long-term debt	971	7,013
Weighted-average interest rate (as a percent)	5.80%
Payments under long-term debt obligations
Long-term debt	971	7,013
Capital lease obligations \| Land and structures (terminals)
Long-term debt obligations
Long-term debt	960
Payments under long-term debt obligations
Due in one year or less	206
Due after one year through two years	213
Due after two years through three years	219
Due after three years through four years	226
Due after four years through five years	232
Due after five years	19
Total payments	1,115
Less amounts representing interest	155
Long-term debt	960
Capital lease obligations \| Service, office, and other equipment
Long-term debt obligations
Long-term debt	11
Payments under long-term debt obligations
Due in one year or less	11
Total payments	11
Long-term debt	$ 11

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Represents aggregate future amounts due of contractually required rental payments on leases meeting the criteria for capitalization and maturities on long-term debt, including interest.

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Represents amount of contractually required rental payments on leases meeting the criteria for capitalization and maturities on long-term debt, including interest, due within one year of the latest balance sheet date presented.

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Represents amount of contractually required rental payments on leases meeting the criteria for capitalization and maturities on long-term debt, including interest, due after four and within five years of the latest balance sheet date presented.

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Represents amount of contractually required rental payments on leases meeting the criteria for capitalization and maturities on long-term debt, including interest, due after three and within four years of the latest balance sheet date presented.

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Represents amount of contractually required rental payments on leases meeting the criteria for capitalization and maturities on long-term debt, including interest, due after two and within three years of the latest balance sheet date presented.

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Represents amount of contractually required rental payments on leases meeting the criteria for capitalization and maturities on long-term debt, including interest, due after one and within two years of the latest balance sheet date presented.

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Represents the interest amount by which the contractually required payments on capital leases and long-term debt are reduced to calculate the present value of the long-term debt and capital lease obligations.

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No definition available.

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Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

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

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Weighted average interest rate of debt outstanding.

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Amount of long-term debt and capital lease obligation due after one year or beyond the normal operating cycle, if longer.

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-Name Accounting Standards Codification

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-Number Topic 6

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Amount of long-term debt and capital leases due within one year or the normal operating cycle, if longer.

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Amount of long-term debt and capital lease obligations including current maturities.

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