XML 52 R34.htm IDEA: XBRL DOCUMENT
v3.6.0.2

EMPLOYEE BENEFIT PLANS (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2016
EMPLOYEE BENEFIT PLANS |
Schedule of changes in benefit obligations and plan assets and disclosure of funded status and accumulated benefit obligation of nonunion defined benefit plans | The following table discloses the changes in benefit obligations and plan assets of the Company’s nonunion defined benefit plans for years ended December 31, the measurement date of the plans:
|  | Nonunion Defined |  | Supplemental |  | Postretirement |
|  | Benefit Pension Plan |  | Benefit Plan |  | Health Benefit Plan |
|  | 2016 |  | 2015 |  | 2016 |  | 2015 |  | 2016 |  | 2015 |
|  | (in thousands) |
Change in benefit obligations |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Benefit obligations at beginning of year |  | $ | 159,607 |  | $ | 174,410 |  | $ | 4,917 |  | $ | 6,782 |  | $ | 24,616 |  | $ | 22,116 |
Service cost |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 429 |  |  | 406 |
Interest cost |  |  | 4,572 |  |  | 5,200 |  |  | 130 |  |  | 123 |  |  | 1,017 |  |  | 913 |
Actuarial (gain) loss(1) |  |  | 4,202 |  |  | 494 |  |  | (7) |  |  | (47) |  |  | 133 |  |  | 1,806 |
Benefits paid |  |  | (16,896) |  |  | (20,892) |  |  | (246) |  |  | (1,941) |  |  | (663) |  |  | (625) |
Settlement loss |  |  | 521 |  |  | 395 |  |  | — |  |  | — |  |  | — |  |  | — |
Benefit obligations at end of year |  |  | 152,006 |  |  | 159,607 |  |  | 4,794 |  |  | 4,917 |  |  | 25,532 |  |  | 24,616 |
Change in plan assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair value of plan assets at beginning of year |  |  | 136,917 |  |  | 158,265 |  |  | — |  |  | — |  |  | — |  |  | — |
Actual return (loss) on plan assets |  |  | 11,384 |  |  | (506) |  |  | — |  |  | — |  |  | — |  |  | — |
Employer contributions |  |  | 13,400 |  |  | 50 |  |  | 246 |  |  | 1,941 |  |  | 663 |  |  | 625 |
Benefits paid |  |  | (16,896) |  |  | (20,892) |  |  | (246) |  |  | (1,941) |  |  | (663) |  |  | (625) |
Fair value of plan assets at end of year |  |  | 144,805 |  |  | 136,917 |  |  | — |  |  | — |  |  | — |  |  | — |
Funded status at end of year |  | $ | (7,201) |  | $ | (22,690) |  | $ | (4,794) |  | $ | (4,917) |  | $ | (25,532) |  | $ | (24,616) |
Accumulated benefit obligation |  | $ | 152,006 |  | $ | 159,607 |  | $ | 4,794 |  | $ | 4,917 |  | $ | 25,532 |  | $ | 24,616 |
| (1) |  | The actuarial loss on the nonunion defined benefit pension plan was higher for 2016, primarily due to a decrease in the discount rate used to remeasure the plan obligation at December 31, 2016 versus December 31, 2015.
Schedule of amounts recognized in the consolidated balance sheets related to nonunion defined benefit plans | Amounts recognized in the consolidated balance sheets at December 31 consisted of the following:
|  | Nonunion Defined |  | Supplemental |  | Postretirement |
|  | Benefit Pension Plan |  | Benefit Plan |  | Health Benefit Plan |
|  | 2016 |  | 2015 |  | 2016 |  | 2015 |  | 2016 |  | 2015 |
|  | (in thousands) |
Current liabilities (included in accrued expenses) |  | $ | — |  | $ | — |  | $ | (989) |  | $ | (246) |  | $ | (690) |  | $ | (736) |
Noncurrent liabilities (included in pension and postretirement liabilities) |  |  | (7,201) |  |  | (22,690) |  |  | (3,805) |  |  | (4,671) |  |  | (24,842) |  |  | (23,880) |
Liabilities recognized |  | $ | (7,201) |  | $ | (22,690) |  | $ | (4,794) |  | $ | (4,917) |  | $ | (25,532) |  | $ | (24,616) |
Summary of the components of net periodic benefit cost | The following is a summary of the components of net periodic benefit cost for the Company’s nonunion benefit plans for the years ended December 31:
|  | Nonunion Defined |  | Supplemental |  | Postretirement |
|  | Benefit Pension Plan |  | Benefit Plan |  | Health Benefit Plan |
|  | 2016 |  | 2015 |  | 2014 |  | 2016 |  | 2015 |  | 2014 |  | 2016 |  | 2015 |  | 2014 |
|  | (in thousands) |  |  |  |
Service cost |  | $ | — |  | $ | — |  | $ | — |  | $ | — |  | $ | — |  | $ | — |  | $ | 429 |  | $ | 406 |  | $ | 280 |
Interest cost |  |  | 4,572 |  |  | 5,200 |  |  | 6,039 |  |  | 130 |  |  | 123 |  |  | 184 |  |  | 1,017 |  |  | 913 |  |  | 788 |
Expected return on plan assets |  |  | (8,607) |  |  | (9,180) |  |  | (10,419) |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Amortization of prior service credit |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (190) |  |  | (190) |  |  | (190) |
Pension settlement expense |  |  | 3,023 |  |  | 3,202 |  |  | 5,880 |  |  | 206 |  |  | — |  |  | 715 |  |  | — |  |  | — |  |  | — |
Amortization of net actuarial loss(1) |  |  | 4,087 |  |  | 3,218 |  |  | 2,398 |  |  | 152 |  |  | 159 |  |  | 214 |  |  | 705 |  |  | 853 |  |  | 93 |
Net periodic benefit cost |  | $ | 3,075 |  | $ | 2,440 |  | $ | 3,898 |  | $ | 488 |  | $ | 282 |  | $ | 1,113 |  | $ | 1,961 |  | $ | 1,982 |  | $ | 971 |
| (1) |  | The Company amortizes actuarial losses over the average remaining active service period of the plan participants and does not use a corridor approach.
Summary of pension settlement distributions and settlement expense | The following is a summary of the pension settlement distributions and pension settlement expense for the years ended December 31:
|  | Nonunion Defined |  | Supplemental |
|  | Benefit Pension Plan |  | Benefit Plan |
|  | 2016(1) |  | 2015(1) |  | 2014(2) |  | 2016 |  | 2015(3) |  | 2014 |
|  | (in thousands, except per share data) |
Pension settlement distributions |  | $ | 16,515 |  | $ | 20,622 |  | $ | 57,518 |  | $ | 246 |  | $ | 1,941 |  | $ | 853 |
Pension settlement expense, pre-tax |  | $ | 3,023 |  | $ | 3,202 |  | $ | 5,880 |  | $ | 206 |  | $ | — |  | $ | 715 |
Pension settlement expense per diluted share, net of taxes |  | $ | 0.07 |  | $ | 0.07 |  | $ | 0.14 |  | $ | 0.01 |  | $ | — |  | $ | 0.02 |
| (1) |  | Pension settlement distributions represent lump‑sum benefit distributions paid.
| (2) |  | Pension settlement distributions represent $32.1 million of lump‑sum benefit distributions and a $25.4 million nonparticipating annuity contract purchase.
| (3) |  | The 2015 SBP distribution represents the portion of a benefit related to an officer retirement that occurred in 2014 which was delayed for six months after retirement in accordance with IRC Section 409A. The pension settlement expense related to this distribution was recognized in 2014.
Pre-tax amounts included in accumulated other comprehensive loss that have not yet been recognized in net periodic benefit cost | Included in accumulated other comprehensive loss at December 31 were the following pre‑tax amounts that have not yet been recognized in net periodic benefit cost:
|  | Nonunion Defined |  | Supplemental |  | Postretirement |
|  | Benefit Pension Plan |  | Benefit Plan |  | Health Benefit Plan |
|  | 2016 |  | 2015 |  | 2016 |  | 2015 |  | 2016 |  | 2015 |
|  | (in thousands) |
Unrecognized net actuarial loss |  | $ | 23,294 |  | $ | 28,457 |  | $ | 635 |  | $ | 1,001 |  | $ | 5,708 |  | $ | 6,280 |
Unrecognized prior service credit |  |  | — |  |  | — |  |  | — |  |  | — |  |  | (317) |  |  | (507) |
Total |  | $ | 23,294 |  | $ | 28,457 |  | $ | 635 |  | $ | 1,001 |  | $ | 5,391 |  | $ | 5,773 |
Pre-tax amounts, which are reported within accumulated other comprehensive loss, expected to be recognized as components of net periodic benefit cost in the next fiscal year | The following amounts, which are reported within accumulated other comprehensive loss at December 31, 2016 are expected to be recognized as components of net periodic benefit cost in 2017 on a pre‑tax basis. (Amounts exclude the effect of pension settlements, which the Company will incur for the nonunion defined benefit pension plan.)
|  | Nonunion |  | Supplemental |  | Postretirement |
|  | Defined Benefit |  | Benefit |  | Health |
|  | Pension Plan |  | Plan |  | Benefit Plan |
|  | (in thousands) |
Unrecognized net actuarial loss |  | $ | 2,960 |  | $ | 109 |  | $ | 620 |
Unrecognized prior service credit |  |  | — |  |  | — |  |  | (190) |
Total |  | $ | 2,960 |  | $ | 109 |  | $ | 430 |
Weighted-average assumptions used to determine benefit obligations and net periodic benefit cost for nonunion defined benefit plans | Weighted‑average assumptions used to determine nonunion benefit obligations at December 31 were as follows:
|  | Nonunion Defined |  | Supplemental |  | Postretirement |
|  | Benefit Pension Plan |  | Benefit Plan |  | Health Benefit Plan |
|  | 2016 |  | 2015 |  | 2016 |  | 2015 |  | 2016 |  | 2015 |
Discount rate |  | 3.4 | % | 3.5 | % | 2.7 | % | 2.6 | % | 4.0 | % | 4.2 | %
Weighted‑average assumptions used to determine net periodic benefit cost for the Company’s nonunion benefit plans for the years ended December 31 were as follows:
|  | Nonunion Defined |  | Supplemental |  | Postretirement |
|  | Benefit Pension Plan |  | Benefit Plan |  | Health Benefit Plan |
|  | 2016(1) |  | 2015(2) |  | 2014(3) |  | 2016 |  | 2015 |  | 2014(4) |  | 2016 |  | 2015 |  | 2014 |
Discount rate |  | 3.5 | % | 3.2 | % | 3.8 | % | 2.6 | % | 2.5 | % | 2.8 | % | 4.2 | % | 3.9 | % | 4.7 | %
Expected return on plan assets |  | 6.5 | % | 6.5 | % | 6.5 | % | N/A |  | N/A |  | N/A |  | N/A |  | N/A |  | N/A |
| (1) |  | The discount rate presented was used to determine the first quarter 2016 expense, and the interim discount rate established upon each quarterly settlement in 2016 of 3.0%, 2.7%, and 2.7% was used to calculate the expense/credit for the second, third, and fourth quarter of 2016, respectively.
| (2) |  | The discount rate presented was used to determine the first quarter 2015 credit, and the interim discount rate established upon each quarterly settlement in 2015 of 3.0%, 3.5%, and 3.4% was used to calculate the expense/credit for the second, third, and fourth quarter of 2015, respectively.
| (3) |  | The discount rate presented was used to determine the first quarter 2014 credit, and the interim discount rate established upon each quarterly settlement in 2014 of 3.5%, 3.3%, and 3.4% was used to calculate the credit for the second, third, and fourth quarter of 2014, respectively.
| (4) |  | The discount rate presented was used to determine expense for the first ten months of 2014 and the discount rate of 2.5% established upon the October 31, 2014 settlement was used to calculate expense for the last two months of 2014.
Schedule of the assumed health care cost trend rates for the postretirement health benefit plan | The assumed health care cost trend rates for the Company’s postretirement health benefit plan at December 31 were as follows:
|  | 2016 |  | 2015
Health care cost trend rate assumed for next year |  | 8.0 | % |  | 6.7 | %
Rate to which the cost trend rate is assumed to decline |  | 4.5 | % |  | 4.5 | %
Year that the rate reaches the cost trend assumed rate |  | 2031 |  |  | 2030 |
Effects of one-percentage-point change in assumed health care cost trend rates on the postretirement health benefit plan | A one‑percentage‑point change in assumed health care cost trend rates would have the following effects on the Company’s postretirement health benefit plan for the year ended December 31, 2016:
|  | One Percentage Point |
|  | Increase |  | Decrease |
|  | (in thousands) |
Effect on total of service and interest cost components |  | $ | 322 |  | $ | (252) |
Effect on postretirement benefit obligation |  | $ | 5,059 |  | $ | (4,036) |
Schedule of estimated future benefit payments for nonunion defined benefit plans | Estimated future benefit payments from the Company’s nonunion defined benefit pension (paid from trust assets), SBP, and postretirement health benefit plans, which reflect expected future service as appropriate, as of December 31, 2016 are as follows:
|  | Nonunion |  | Supplemental |  | Postretirement |
|  | Defined Benefit |  | Benefit |  | Health |
|  | Pension Plan |  | Plan |  | Benefit Plan |
|  | (in thousands) |
2017 |  | $ | 26,608 |  | $ | 989 |  | $ | 690 |
2018 |  | $ | 12,386 |  | $ | — |  | $ | 777 |
2019 |  | $ | 12,372 |  | $ | 3,107 |  | $ | 854 |
2020 |  | $ | 12,543 |  | $ | — |  | $ | 928 |
2021 |  | $ | 12,031 |  | $ | — |  | $ | 1,003 |
2022-2026 |  | $ | 51,341 |  | $ | — |  | $ | 6,202 |
Weighted-average target, acceptable ranges, and actual asset allocations of the nonunion defined benefit pension plan | The weighted‑average target, acceptable ranges, and actual asset allocations of the Company’s nonunion defined benefit pension plan at December 31 are summarized in the following table:
|  | 2016 |  |  |
|  | Target |  |  | Acceptable |  |  | Weighted-Average Allocation |
|  | Allocation |  |  | Range |  |  | 2016 |  | 2015 |
Equity Securities |  |  |  |  |  |  |  |  |  |  |  |  |  |
Large Cap U.S. Equity |  | 13.0 | % |  | 8.0 | % | - | 20.0 | % |  | 14.0 | % | 17.2 | %
Mid Cap U.S. Equity |  | 9.0 |  |  | 7.0 | % | - | 11.0 | % |  | 9.4 |  | 10.4 |
Small Cap U.S. Equity |  | 9.0 |  |  | 7.0 | % | - | 11.0 | % |  | 10.0 |  | 10.3 |
International Equity |  | 14.0 |  |  | 10.0 | % | - | 18.0 | % |  | 14.4 |  | 17.1 |
Income Securities |  |  |  |  |  |  |  |  |  |  |  |  |  |
Debt Instruments |  | 25.0 |  |  | 20.0 | % | - | 30.0 | % |  | 25.0 |  | 19.5 |
Floating Rate Loan Fund |  | 10.0 |  |  | 3.0 | % | - | 15.0 | % |  | 10.8 |  | 11.6 |
Cash Equivalents |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash and Cash Equivalents |  | 20.0 |  |  | 0.0 | % | - | 25.0 | % |  | 16.4 |  | 13.9 |
|  | 100.0 | % |  |  |  |  |  |  |  | 100.0 | % | 100.0 | %
Fair value of the nonunion defined benefit pension plan assets, by major asset category and fair value hierarchy level | The fair value of the Company’s nonunion defined benefit pension plan assets at December 31, 2016, by major asset category and fair value hierarchy level (see Fair Value Measurements accounting policy in Note B), were as follows:
|  |  |  |  | Fair Value Measurements Using |
|  |  |  |  | Quoted Prices |  | Significant |  | Significant |
|  |  |  |  | In Active |  | Observable |  | Unobservable |
|  |  |  |  | Markets |  | Inputs |  | Inputs |
|  | Total |  | (Level 1) |  | (Level 2) |  | (Level 3) |
|  | (in thousands) |
Cash and Cash Equivalents(1) |  | $ | 23,696 |  | $ | 23,696 |  | $ | — |  | $ | — |
Debt Instruments(2) |  |  | 36,245 |  |  | — |  |  | 36,245 |  |  | — |
Floating Rate Loans(3) |  |  | 15,687 |  |  | 15,687 |  |  | — |  |  | — |
Large Cap U.S. Equity |  |  | 20,208 |  |  | 20,208 |  |  | — |  |  | — |
Mid Cap U.S. Equity |  |  | 13,597 |  |  | 13,597 |  |  | — |  |  | — |
Small Cap U.S. Equity |  |  | 14,561 |  |  | 14,561 |  |  | — |  |  | — |
International Equity |  |  | 20,811 |  |  | 20,811 |  |  | — |  |  | — |
|  | $ | 144,805 |  | $ | 108,560 |  | $ | 36,245 |  | $ | — |
| (1) |  | Consists primarily of money market mutual funds.
| (2) |  | Includes corporate debt instruments (81%), mortgage-backed instruments (10%), treasury instruments (7%), municipal debt instruments (1%), and agency debt instruments (1%) which are priced using daily bid prices. The fair value measurements are provided by a pricing service which uses the market approach with inputs derived from observable market data.
| (3) |  | Consists of a floating rate loan mutual fund.
The fair value of the Company’s nonunion defined benefit pension plan assets at December 31, 2015, by major asset category and fair value hierarchy level (see Fair Value Measurements accounting policy in Note B), were as follows:
|  |  |  |  | Fair Value Measurements Using |
|  |  |  |  | Quoted Prices |  | Significant |  | Significant |
|  |  |  |  | In Active |  | Observable |  | Unobservable |
|  |  |  |  | Markets |  | Inputs |  | Inputs |
|  | Total |  | (Level 1) |  | (Level 2) |  | (Level 3) |
|  | (in thousands) |
Cash and Cash Equivalents(1) |  | $ | 19,079 |  | $ | 19,079 |  | $ | — |  | $ | — |
Debt Instruments(2) |  |  | 26,662 |  |  | — |  |  | 26,662 |  |  | — |
Floating Rate Loans(3) |  |  | 15,868 |  |  | 15,868 |  |  | — |  |  | — |
Large Cap U.S. Equity |  |  | 23,459 |  |  | 23,459 |  |  | — |  |  | — |
Mid Cap U.S. Equity |  |  | 14,276 |  |  | 14,276 |  |  | — |  |  | — |
Small Cap U.S. Equity |  |  | 14,135 |  |  | 14,135 |  |  | — |  |  | — |
International Equity |  |  | 23,438 |  |  | 23,438 |  |  | — |  |  | — |
|  | $ | 136,917 |  | $ | 110,255 |  | $ | 26,662 |  | $ | — |
| (1) |  | Consists primarily of money market mutual funds.
| (2) |  | Includes corporate debt instruments (74%), mortgage‑backed instruments (17%), treasury instruments (6%), municipal debt instruments (2%), and agency debt instruments (1%) which are priced using daily bid prices. The fair value measurements are provided by a pricing service which uses the market approach with inputs derived from observable market data.
| (3) |  | Consists of a floating rate loan mutual fund.
Schedule of multiemployer pension funds and key participation information |
|  |  |  | Pension |  | FIP/RP |  |  |  |  |  |  |  |  |  |  |
|  |  |  | Protection Act |  | Status |  | Contributions (d) |  |
|  | EIN/Pension |  | Zone Status (b) |  | Pending/ |  | (in thousands) |  | Surcharge
Legal Name of Plan |  | Plan Number (a) |  | 2016 |  | 2015 |  | Implemented (c) |  | 2016 |  | 2015 |  | 2014 |  | Imposed (e)
Central States, Southeast and Southwest Areas Pension Plan(1)(2) |  | 36-6044243 |  | Critical and Declining |  | Critical and Declining |  | Implemented(3) |  | $ | 77,891 |  | $ | 77,491 |  | $ | 74,001 |  | No
Western Conference of Teamsters Pension Plan(2) |  | 91-6145047 |  | Green |  | Green |  | No |  |  | 25,075 |  |  | 24,474 |  |  | 23,030 |  | No
Central Pennsylvania Teamsters Defined Benefit Plan(1)(2) |  | 23-6262789 |  | Green |  | Green |  | No |  |  | 13,381 |  |  | 13,147 |  |  | 12,810 |  | No
I. B. of T. Union Local No. 710 Pension Fund(5)(6) |  | 36-2377656 |  | Green(4) |  | Green(4) |  | No |  |  | 9,670 |  |  | 10,020 |  |  | 9,186 |  | No
All other plans in the aggregate |  |  |  |  |  |  |  |  |  |  | 28,122 |  |  | 26,766 |  |  | 25,150 |  |
Total multiemployer pension contributions paid(7) |  |  |  |  |  |  |  |  |  | $ | 154,139 |  | $ | 151,898 |  | $ | 144,177 |  |
Table Heading Definitions
| (a) |  | The “EIN/Pension Plan Number” column provides the Federal Employer Identification Number (EIN) and the three‑digit plan number, if applicable.
| (b) |  | Unless otherwise noted, the most recent PPA zone status available in 2016 and 2015 is for the plan’s year‑end status at December 31, 2015 and 2014, respectively. The zone status is based on information received from the plan and was certified by the plan’s actuary. Green zone funds are those that are in neither endangered, critical, or critical and declining status and generally have a funded percentage of at least 80%.
| (c) |  | The “FIP/RP Status Pending/Implemented” column indicates if a funding improvement plan (FIP) or a rehabilitation plan (RP), if applicable, is pending or has been implemented.
| (d) |  | Amounts reflect contributions made in the respective year and differ from amounts expensed during the year.
| (e) |  | The surcharge column indicates if a surcharge was paid by ABF Freight to the plan.
| (1) |  | ABF Freight System, Inc. was listed by the plan as providing more than 5% of the total contributions to the plan for the plan years ended December 31, 2015 and 2014.
| (2) |  | Information for this fund was obtained from the annual funding notice, other notices received from the plan, and the Form 5500 filed for the plan years ended December 31, 2015 and 2014.
| (3) |  | Adopted a rehabilitation plan effective March 25, 2008 as updated. Utilized amortization extension granted by the IRS effective December 31, 2003.
| (4) |  | PPA zone status relates to plan years February 1, 2015 – January 31, 2016 and February 1, 2014 – January 31, 2015.
| (5) |  | The Company was listed by the plan as providing more than 5% of the total contributions to the plan for the plan years ended January 31, 2016 and 2015.
| (6) |  | Information for this fund was obtained from the annual funding notice, other notices received from the plan, and the Form 5500 filed for the plan years ended January 31, 2016 and January 31, 2015.
| (7) |  | Contribution levels can be impacted by several factors such as changes in business levels and the related time worked by contractual employees, contractual rate increases for pension benefits, and the specific funding structure, which differs among funds. The pension contribution rate for contractual employees increased an average of approximately 2.8%, 1.3%, and 0.8% effective primarily on August 1, 2016, 2015, and 2014, respectively. The Supplemental Negotiating Committee for the Central States Pension Plan approved no pension contribution increase effective August 1, 2016, 2015, and 2014. The Supplemental Negotiating Committee for the Western Conference of Teamsters Pension Plan approved no pension increase effective August 1, 2016, 2015, and 2014. The year‑over‑year changes in multiemployer pension plan contributions presented above were also influenced by changes in Asset-Based business levels.

X
- Definition Tabular disclosure of the fair value of each major category of plan assets, and the level within the fair value hierarchy in which the fair value measurements fall. + References No definition available. + Details
Name: | arcb_ScheduleOfDefinedBenefitPlanFairValueOfPlanAssetsByMajorAssetCategoryAndFairValueHierarchyLevelTableTextBlock
Namespace Prefix: | arcb_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the weighted-average target, acceptable ranges, and actual asset allocation percentage by major asset class of defined benefit plan assets. + References No definition available. + Details
Name: | arcb_ScheduleOfDefinedBenefitPlanTargetAcceptableRangesAndActualAssetAllocationsTableTextBlock
Namespace Prefix: | arcb_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of net funded status of pension plans and/or other employee benefit plans and disclosure of accumulated benefit obligation. + References No definition available. + Details
Name: | arcb_ScheduleOfNetFundedStatusAndChangesInAccumulatedBenefitObligationAndPlanAssetsTableTextBlock
Namespace Prefix: | arcb_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of pension settlement distributions and pension settlement expense related to employee benefit plans. + References No definition available. + Details
Name: | arcb_ScheduleOfPensionSettlementDistributionsAndPensionSettlementExpenseTableTextBlock
Namespace Prefix: | arcb_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_CompensationAndRetirementDisclosureAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the amounts related to pension plans and/or other employee benefit plans in accumulated other comprehensive income (loss) expected to be recognized as components of net periodic benefit cost over the next fiscal year, including the net gain (loss), net prior service cost or credit, and net transition asset or obligation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (s) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
Name: | us-gaap_ScheduleOfAmountsInAccumulatedOtherComprehensiveIncomeLossToBeRecognizedOverNextFiscalYearTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the amounts that are recognized in the balance sheet (or statement of financial position) for pension plans and/or other employee benefit plans, showing separately the assets and current and noncurrent liabilities (if applicable) recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
Name: | us-gaap_ScheduleOfAmountsRecognizedInBalanceSheetTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the assumptions used to determine for pension plans and/or other employee benefit plans the benefit obligation and net benefit cost, including assumed discount rates, rate increase in compensation increase, and expected long-term rates of return on plan assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
Name: | us-gaap_ScheduleOfAssumptionsUsedTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the effect of a one-percentage-point increase and the effect of a one-percentage-point decrease in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs and the accumulated postretirement benefit obligation for health care benefits. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (m) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
Name: | us-gaap_ScheduleOfEffectOfOnePercentagePointChangeInAssumedHealthCareCostTrendRatesTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of benefits expected to be paid by pension plans and/or other employee benefit plans in each of the next five fiscal years and in the aggregate for the five fiscal years thereafter. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
Name: | us-gaap_ScheduleOfExpectedBenefitPaymentsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the assumed health care cost trend rates for the next year used to measure the expected cost of benefits covered by the plans, including the ultimate trend rate(s) and when that rate is expected to be achieved. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (l) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
Name: | us-gaap_ScheduleOfHealthCareCostTrendRatesTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the quantitative and qualitative information related to multiemployer plans in which the employer participates. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947 + Details
Name: | us-gaap_ScheduleOfMultiemployerPlansTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
Name: | us-gaap_ScheduleOfNetBenefitCostsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of the amounts related to pension plans and/or other employee benefit plans in accumulated other comprehensive income or loss that have not yet been recognized as components of net periodic benefit cost, such as the net gain (loss), net prior service cost or credit, and net transition asset or obligation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (j) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
Name: | us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration