Saia (SAIA) 10-K 26 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 25, 2016	Jun. 30, 2015
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Trading Symbol	SAIA
Entity Registrant Name	SAIA INC
Entity Central Index Key	1,177,702
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		25,186,278
Entity Public Float			$ 987,303,912

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current Assets:
Cash and cash equivalents	$ 124	$ 4,367
Accounts receivable, less allowances of $3,548 in 2015 and $3,868 in 2014	124,222	128,367
Prepaid expenses and other	14,197	13,687
Income tax receivable	15,745	18,335
Other current assets	4,701	5,420
Total current assets	158,989	170,176
Property and Equipment, at cost	995,514	891,145
Less-accumulated depreciation	456,335	407,505
Net property and equipment	539,179	483,640
Goodwill	12,025	5,231
Identifiable Intangibles, net	14,961	2,943
Other Noncurrent Assets	4,039	4,995
Total assets	729,193	666,985
Current Liabilities:
Accounts payable	54,754	42,388
Wages, vacation and employees’ benefits	27,834	28,777
Claims and insurance accruals	26,903	29,314
Other current liabilities	19,457	20,862
Current portion of long-term debt	12,432	9,138
Total current liabilities	141,380	130,479
Other Liabilities:
Long-term debt, less current portion	56,540	73,897
Deferred income taxes	67,417	58,946
Claims, insurance and other	35,967	36,757
Total other liabilities	$ 159,924	$ 169,600
Commitments and Contingencies
Stockholders’ Equity:
Preferred stock, $0.001 par value, 50,000 shares authorized, none issued and outstanding
Common stock, $0.001 par value, 50,000,000 shares authorized, 25,141,799 and 24,871,806 shares issued and outstanding at December 31, 2015 and December 31, 2014, respectively	$ 25	$ 25
Additional paid-in-capital	230,593	223,713
Deferred compensation trust, 165,971 and 193,607 shares of common stock at cost at December 31, 2015 and December 31, 2014, respectively	(3,102)	(2,189)
Retained earnings	200,373	145,357
Total stockholders’ equity	427,889	366,906
Total liabilities and stockholders’ equity	$ 729,193	$ 666,985

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Allowance of accounts receivable	$ 3,548	$ 3,868
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	50,000	50,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	50,000,000	50,000,000
Common stock, shares issued	25,141,799	24,871,806
Common stock, shares outstanding	25,141,799	24,871,806
Deferred compensation trust	165,971	193,607

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Operating Revenue	$ 1,221,311	$ 1,272,321	$ 1,139,094
Operating Expenses:
Salaries, wages and employees’ benefits	670,173	639,633	572,487
Purchased transportation	70,611	99,610	72,975
Fuel, operating expenses and supplies	261,387	314,788	306,364
Operating taxes and licenses	37,003	36,028	36,513
Claims and insurance	26,832	37,563	25,494
Depreciation and amortization	65,020	59,022	51,564
Operating (gains) losses, net	310	(16)	(721)
Total operating expenses	1,131,336	1,186,628	1,064,676
Operating Income	89,975	85,693	74,418
Nonoperating Expenses (Income):
Interest expense	4,107	4,564	6,490
Other, net	(95)	(99)	(217)
Nonoperating expenses, net	4,012	4,465	6,273
Income Before Income Taxes	85,963	81,228	68,145
Income Tax Expense	30,947	29,237	24,518
Net Income	$ 55,016	$ 51,991	$ 43,627
Weighted average common shares outstanding – basic	24,919	24,505	24,154
Weighted average common shares outstanding – diluted	25,471	25,463	25,205
Basic Earnings Per Share	$ 2.21	$ 2.12	$ 1.81
Diluted Earnings Per Share	$ 2.16	$ 2.04	$ 1.73

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Deferred Compensation Trust [Member]	Retained Earnings [Member]
Beginning Balance at Dec. 31, 2012	$ 254,519	$ 24	$ 206,969	$ (2,213)	$ 49,739
Beginning Balance, Shares at Dec. 31, 2012		24,088,417
Stock compensation for options and long-term incentives	2,227		2,227
Stock compensation for options and long-term incentives, Shares		16,499
Director deferred shares for annual deferral elections	674		674
3 for 2 Stock Split	(40)		(40)
3 for 2 Stock Split, Shares		(864)
Exercise of stock options, including tax benefits	4,173		4,173
Exercise of stock options, including tax benefits, Shares		263,064
Shares issued for long-term incentive awards, net of shares withheld for taxes	(1,162)		(1,162)
Shares issued for long-term incentive awards, net of shares withheld for taxes, Shares		111,428
Deferred tax adjustment for long-term incentive plan	774		774
Purchase of shares by Deferred Compensation Trust	(158)			(158)
Sale of shares by Deferred Compensation Trust	158		33	125
Net income	43,627				43,627
Ending Balance at Dec. 31, 2013	304,792	$ 24	213,648	(2,246)	93,366
Ending Balance, Shares at Dec. 31, 2013		24,478,544
Stock compensation for options and long-term incentives	3,393		3,393
Stock compensation for options and long-term incentives, Shares		6,023
Director deferred shares for annual deferral elections	773		773
Exercise of stock options, including tax benefits	6,652	$ 1	6,651
Exercise of stock options, including tax benefits, Shares		318,321
Shares issued for long-term incentive awards, net of shares withheld for taxes	(1,667)		(1,667)
Shares issued for long-term incentive awards, net of shares withheld for taxes, Shares		68,918
Deferred tax adjustment for long-term incentive plan	971		971
Purchase of shares by Deferred Compensation Trust	(53)			(53)
Sale of shares by Deferred Compensation Trust	54		(56)	110
Net income	51,991				51,991
Ending Balance at Dec. 31, 2014	366,906	$ 25	223,713	(2,189)	145,357
Ending Balance, Shares at Dec. 31, 2014		24,871,806
Stock compensation for options and long-term incentives	2,983		2,983
Stock compensation for options and long-term incentives, Shares		37,311
Director deferred shares for annual deferral elections	895		895
Exercise of stock options, including tax benefits	$ 2,533		2,533
Exercise of stock options, including tax benefits, Shares	118,090	116,088
Shares issued for long-term incentive awards, net of shares withheld for taxes	$ (3,118)		(3,118)
Shares issued for long-term incentive awards, net of shares withheld for taxes, Shares		116,594
Deferred tax adjustment for long-term incentive plan	2,674		2,674
Purchase of shares by Deferred Compensation Trust	(2,227)			(2,227)
Sale of shares by Deferred Compensation Trust	2,227		913	1,314
Net income	55,016				55,016
Ending Balance at Dec. 31, 2015	$ 427,889	$ 25	$ 230,593	$ (3,102)	$ 200,373
Ending Balance, Shares at Dec. 31, 2015		25,141,799

Consolidated Statements of Sto6

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Tax benefits exercise stock options	$ 1,056	$ 2,984	$ 1,356
Common Stock [Member]
Tax benefits exercise stock options	1,056	2,984	1,356
Additional Paid-in Capital [Member]
Tax benefits exercise stock options	$ 1,056	$ 2,984	$ 1,356

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Activities:
Net income	$ 55,016	$ 51,991	$ 43,627
Noncash items included in net income:
Depreciation and amortization	65,020	59,022	51,564
Provision for doubtful accounts	1,463	1,942	2,227
Deferred income taxes	8,420	9,462	12,098
Loss (gain) from property disposals, net	310	(17)	(721)
Stock-based compensation	3,878	4,166	2,902
Changes in operating assets and liabilities:
Accounts receivable	6,896	(12,372)	(13,350)
Accounts payable	(382)	(8,590)	5,479
Other working capital items, net	(84)	(11,215)	(5,213)
Claims, insurance and other	(821)	5,260	392
Other, net	2,998	2,521	2,307
Net cash provided by operating activities	142,714	102,170	101,312
Investing Activities:
Acquisition of business, net of cash received	(22,238)
Acquisition of property and equipment	(86,499)	(97,750)	(126,358)
Proceeds from disposal of property and equipment	818	2,905	4,338
Net cash used in investing activities	(107,919)	(94,845)	(122,020)
Financing Activities:
Repayment of revolving credit agreement	(280,461)	(340,540)	(223,798)
Borrowing of revolving credit agreement	249,994	337,223	262,125
Proceeds from stock option exercises (including excess tax benefits)	2,533	7,623	4,948
Repayment of senior notes	(7,143)	(7,143)	(22,143)
Repayment of capital leases	(3,507)	(280)
Other financing activity	(454)		(586)
Net cash (used in) provided by financing activities	(39,038)	(3,117)	20,546
Net Increase (Decrease) in Cash and Cash Equivalents	(4,243)	4,208	(162)
Cash and cash equivalents, beginning of period	4,367	159	321
Cash and cash equivalents, end of period	124	4,367	$ 159
Non Cash Investing Activities
Equipment financed with capital leases	$ 27,054	$ 16,886

Description of Business and Sum

Description of Business and Summary of Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Description of Business and Summary of Accounting Policies	1. Description of Business and Summary of Accounting Policies Description of Business Saia, Inc. and its subsidiaries (Saia or the Company) are headquartered in Johns Creek, Georgia. The Company offers customers a wide range of less-than-truckload, non-asset truckload, expedited and logistics services across the United States through its wholly-owned subsidiaries. Effective December 31, 2015, the Company’s subsidiaries were as follows: Saia Motor Freight Line, LLC, doing business as Saia LTL Freight; Saia TL Plus, LLC, formerly Robart Transportation, Inc.; Saia Sales, LLC; Saia Logistics Services, LLC, formerly The RL Services Group, LLC; MetroGo, LLC., formed on January 22, 2015; and LinkEx, Inc. acquired on February 2, 2015. The Chief Operating Decision Maker is the Chief Executive Officer who manages the business, regularly reviews financial information and allocates resources. The Company has one operating segment. Basis of Presentation The accompanying consolidated financial statements include the accounts of Saia, Inc. and its wholly-owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in the consolidated financial statements. Common Stock Split On May 16, 2013, the Company announced a three-for-two stock split in the form of a 50 percent stock dividend. The shares were distributed on June 13, 2013 to shareholders of record as of the close of business on the record date of May 31, 2013. In lieu of fractional shares, shareholders received a cash payment based on the closing share price of the Company’s common stock on the record date. All references in this report to common shares outstanding, weighted average common shares and earnings per share amounts have been retroactively restated to reflect this stock split. Use of Estimates Management makes estimates and assumptions when preparing the consolidated financial statements in conformity with U.S. generally accepted accounting principles. These estimates and assumptions affect the amounts reported in the consolidated financial statements and footnotes. Actual results could differ from those estimates. Accounting Pronouncements Adopted During 2015 In April 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2015-03, Interest – Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs In November 2015, the FASB issued ASU 2015-17, Income Taxes (Subtopic 740): Balance Sheet Classification of Deferred Taxes Accounting Pronouncements Not Yet Adopted In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, Summary of Accounting Policies Major accounting policies and practices used in the preparation of the accompanying consolidated financial statements not covered in other notes to the consolidated financial statements are as follows: Cash and Cash Equivalents and Checks Outstanding: Cash and cash equivalents in excess of current operating requirements are invested in short-term interest bearing instruments purchased with original maturities of three months or less and are stated at cost, which approximates market. Checks outstanding in excess of cash on deposit are classified in accounts payable on the accompanying consolidated balance sheets and in operating activities in the accompanying consolidated statements of cash flows. Inventories, fuel and operating supplies: Inventories are carried at average cost and included in other current assets. To mitigate the Company’s risk to rising fuel prices, the Company has implemented fuel surcharge programs and considers effects of these fuel surcharge programs in customer pricing negotiations. Property and Equipment Including Repairs and Maintenance: Property and equipment are carried at cost less accumulated depreciation. Depreciation is computed using the straight-line method based on the following service lives: Years Structures 20 to 25 Tractors 6 to 10 Trailers 10 to 14 Other revenue equipment 10 to 14 Technology equipment and software 3 to 5 Other 3 to 10 At December 31, property and equipment consisted of the following (in thousands): 2015 2014 Land $ 57,506 $ 53,632 Structures 181,769 140,206 Tractors 314,326 290,718 Trailers 256,494 237,262 Other revenue equipment 36,828 37,220 Technology equipment and software 72,707 63,773 Other 75,884 68,334 Total property and equipment, at cost $ 995,514 $ 891,145 Maintenance and repairs are charged to operations while replacements and improvements that extend the asset’s life are capitalized. The Company’s investment in technology equipment and software consists primarily of systems to support customer service and freight management. Depreciation was $63.4 million, $58.4 million and $51.0 million for the years ended December 31, 2015, 2014 and 2013, respectively. Depreciation and amortization expense includes amortization of assets under capital lease. Computer Software Developed or Obtained for Internal Use: The Company capitalizes certain costs associated with developing or obtaining internal-use software. Capitalizable costs include external direct costs of materials and services utilized in developing or obtaining the software and payroll and payroll-related costs for employees directly associated with the development of the project. For the years ended December 31, 2015, 2014, and 2013, the Company capitalized $2.2 million, $1.0 million, and $2.1 million, respectively, of primarily payroll-related costs. Claims and Insurance Accruals: Claims and insurance accruals, both current and long-term, reflect the estimated cost of claims for workers’ compensation (discounted to present value), cargo loss and damage, and bodily injury and property damage not covered by insurance. These costs are included in claims and insurance expense, except for workers’ compensation, which is included in employees’ benefits expense. The liabilities for self-funded retention are included in claims and insurance reserves based on claims incurred. Liabilities for unsettled claims and claims incurred but not yet reported are actuarially determined with respect to workers’ compensation claims and with respect to all other liabilities, estimated based on management’s evaluation of the nature and severity of individual claims and past experience. The former parent of Saia provides guarantees for claims in certain self-insured states that arose prior to September 30, 2002 (See Note 3 for more information regarding the guarantees). Risk retention amounts per occurrence during the three years ended December 31, 2015, were as follows: Workers’ compensation $ 1,000,000 Bodily injury and property damage 2,000,000 Employee medical and hospitalization 350,000 Cargo loss and damage 250,000 The Company’s insurance accruals are presented net of amounts receivable from insurance companies that provide coverage above the Company’s retention. Income Taxes: Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. As required by FASB Accounting Standards Codification (“ASC”) 740, , the Company follows this guidance which defines the threshold for recognizing the benefits of tax-filing positions in the financial statements as “more-likely-than-not” to be sustained by the tax authority. ASC 740 also prescribes a method for computing the tax benefit of such tax positions to be recognized in the financial statements. In addition, it provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosure and transition. Revenue Recognition: Revenue is recognized on a percentage-of-completion basis for shipments in transit while expenses are recognized as incurred. Logistics services engage in some transactions wherein they act as agents. Revenue from these transactions is recorded on a net basis. Net revenue includes billings to customers less third-party charges. Stock-Based Compensation: The Company accounts for its employee stock-based compensation awards in accordance with ASC 718, . ASC 718 requires that all employee stock-based compensation is recognized as an expense in the financial statements and that for equity-classified awards such expenses are measured at the grant date fair value of the award. Stock options are accounted for in accordance with ASC 718 with the expense amortized over the three-year vesting period using a Black-Sholes-Merton model to estimate the fair value of stock options granted to employees. Stock-based performance unit awards are accounted for in accordance with ASC 718 with the expense amortized over the three-year vesting period using a Monte Carlo model to estimate fair value at the date the awards are granted. Credit Risk: The Company routinely grants credit to its customers. The risk of significant loss in trade receivables is substantially mitigated by the Company’s credit evaluation process, short collection terms, low revenue per transaction and services performed for a large number of customers with no single customer representing more than 6.0 percent of consolidated operating revenue. Allowances for potential credit losses are based on historical loss experience, current economic environment, expected trends and customer specific factors. Impairment of Long-Lived Assets: As required by ASC 360, , long-lived assets, such as property, plant and equipment, and purchased intangible assets subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require a long-lived asset or asset group be tested for possible impairment, the Company first compares undiscounted cash flows expected to be generated by that asset or asset group to its carrying value. If the carrying value of the long-lived asset or asset group is not recoverable on an undiscounted cash flow basis, impairment is recognized to the extent that the carrying value exceeds its fair value. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as deemed necessary. The Company has adopted ASU 2011-08, Testing Goodwill for Impairment Intangibles – Goodwill and Other Advertising: The costs of advertising are expensed as incurred. Advertising costs charged to expense were $1.7 million, $1.9 million, and $0.8 million in 2015, 2014 and 2013, respectively. Financial Instruments The carrying amounts of financial instruments including cash and cash equivalents, accounts receivable, accounts payable and short-term debt approximated fair value as of December 31, 2015 and 2014, because of the relatively short maturity of these instruments. See Note 2 for fair value disclosures related to long-term debt.

Debt and Financing Arrangements

Debt and Financing Arrangements	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Debt and Financing Arrangements	2. Debt and Financing Arrangements At December 31, debt consisted of the following (in thousands): December 31, 2015 December 31, 2014 Credit Agreement with Banks, described below $ 14,534 $ 45,000 Senior Notes under a Master Shelf Agreement, described below 14,286 21,429 Capital Leases, described below 40,152 16,606 Total debt 68,972 83,035 Less: current portion of long-term debt 12,432 9,138 Long-term debt, less current portion $ 56,540 $ 73,897 The Company’s liquidity needs arise primarily from capital investment in new equipment, land and structures, information technology and letters of credit required under insurance programs, as well as funding working capital requirements. The Company is party to a revolving credit agreement with a group of banks to fund capital investments, letters of credit and working capital needs. On March 6, 2015, the Company entered into the Fifth Amended and Restated Credit Agreement with its banking group (as amended, the Restated Credit Agreement). The Restated Credit Agreement increased the revolving credit facility availability from $200 million to $250 million and extended the term until March 2020. The Restated Credit Agreement also reduced the interest rate pricing grid and eliminated both the borrowing base and the minimum tangible net worth covenant. On the same date, the Company also entered into the Second Amended and Restated Master Shelf Agreement with its long term note holders (as amended, the Restated Master Shelf Agreement) that made changes to this agreement to conform to certain changes in the Restated Credit Agreement. The Company has pledged certain real estate and facilities, tractors and trailers, accounts receivable and other assets to secure indebtedness under both agreements. Restated Credit Agreement The Restated Credit Agreement is a revolving credit facility for up to $250 million expiring in March 2020. The Restated Credit Agreement also has an accordion feature that allows for an additional $75 million of availability, subject to lender approval. The Restated Credit Agreement provides for a LIBOR rate margin range from 112.5 basis points to 225 basis points, base rate margins from minus 12.5 to plus 50 basis points, an unused portion fee from 20 basis points to 30 basis points and a letter of credit fee range from 112.5 basis points to 225 basis points in each case based on the Company’s leverage ratio. Under the Restated Credit Agreement, the Company must maintain certain financial covenants including a minimum fixed charge coverage ratio and a maximum leverage ratio, among others. The Restated Credit Agreement also provides for a pledge by the Company of certain land and structures, certain tractors, trailers and other personal property and accounts receivable, as defined in the Restated Credit Agreement. At December 31, 2015, the Company had borrowings of $14.5 million and outstanding letters of credit of $44.8 million under the Restated Credit Agreement. At December 31, 2014, the Company had borrowings of $45.0 million and outstanding letters of credit of $47.3 million under the Restated Credit Agreement. The available portion of the Restated Credit Agreement may be used for general corporate purposes, including future capital expenditures, working capital and letter of credit requirements as needed. Restated Master Shelf Agreement On September 20, 2002, the Company issued $100 million in Senior Notes under a $125 million (amended to $150 million in April 2005) Master Shelf Agreement with Prudential Investment Management, Inc. and certain of its affiliates. The Company issued another $25 million in Senior Notes on November 30, 2007 and $25 million in Senior Notes on January 31, 2008 under the same Master Shelf Agreement. The initial $100 million Senior Notes had a fixed interest rate of 7.38 percent. Payments due under the $100 million Senior Notes were interest only until June 30, 2006 and at that time semi-annual principal payments began with the final payment made in December 2013. The November 2007 issuance of $25 million Senior Notes has a fixed interest rate of 6.14 percent. The January 2008 issuance of $25 million Senior Notes has a fixed interest rate of 6.17 percent. Payments due for both $25 million issuances were interest only until June 30, 2011 and at that time semi-annual principal payments began with the final payments due December 31, 2017. Under the terms of the Senior Notes, the Company must maintain certain financial covenants including a minimum fixed charge coverage ratio and a maximum leverage ratio, among others. The Senior Notes also provide for a pledge by the Company of certain land and structures, certain tractors, trailers and other personal property and accounts receivable, as defined in the Senior Notes. Capital Leases The Company is obligated under capital leases which include obligations covering revenue equipment with seven year terms totaling $40.2 million and $16.6 million as of December 31, 2015 and 2014, respectively. Amortization of assets held under the capital leases is included in depreciation and amortization expense. The weighted average interest rate for the capital leases at December 31, 2015 and 2014 is 2.85% and 2.92%, respectively. Other The Company paid cash for interest of $3.0 million, $4.5 million, and $6.1 million for the years ended December 31, 2015, 2014 and 2013, respectively. The estimated fair value of total debt at December 31, 2015 and 2014 is $73.1 million and $83.7 million, respectively. The carrying amount of debt related to the revolving credit facility approximated fair value as of December 31, 2015 and 2014 due to the existence of variable interest rates, which approximate market rates. The fair value of the senior notes is based on undiscounted cash flows at market interest rates for similar issuances of private debt which reflect Level 2 inputs in the fair value hierarchy. The fair value of the capital leases is based on current market interest rates for similar types of financial instruments which reflect Level 2 inputs. The principal maturities of long-term debt for the next five years (in thousands) are as follows: Amount 2016 $ 13,508 2017 13,508 2018 6,365 2019 6,365 2020 20,899 Thereafter 12,449 Total 73,094 Less: Amounts Representing Interest on Capital Leases 4,122 Total $ 68,972

Commitments, Contingencies and

Commitments, Contingencies and Uncertainties	12 Months Ended
	Dec. 31, 2015
Commitments And Contingencies Disclosure [Abstract]
Commitments, Contingencies and Uncertainties	3. Commitments, Contingencies and Uncertainties The Company leases certain service facilities and equipment. Rent expense was $17.9 million, $17.1 million, and $17.9 million for the years ended December 31, 2015, 2014 and 2013, respectively. At December 31, 2015, the Company was committed under non-cancellable operating lease agreements requiring minimum annual rentals payable as follows (in thousands): Amount 2016 $ 14,232 2017 12,646 2018 10,088 2019 7,488 2020 4,875 Thereafter 12,513 Total $ 61,842 Management expects that in the normal course of business, leases will be renewed or replaced as they expire. Capital expenditures committed were $24.7 million at December 31, 2015. As of December 31, 2015 and 2014, the Company had $12.1 million and $1.8 million, respectively, of capital expenditures in accounts payable. Other. YRC Worldwide, Inc. (Yellow) provides guarantees for certain workers’ compensation and casualty claims for which the Company is allocated its pro rata share of letters of credit which Yellow must maintain for these insurance programs. Yellow allocated $1.8 million in letters of credit at December 31, 2015 and 2014 in connection with the Company’s insurance programs for which the Company pays quarterly Yellow’s cost plus 125 basis points. The Company is subject to legal proceedings that arise in the ordinary course of its business. The Company believes that adequate provisions for resolution of all contingencies, claims and pending litigation have been made for probable and estimable losses and that the ultimate outcome of these actions will not have a material adverse effect on its financial condition but could have a material adverse effect on its results of operations in a given quarter or annual period.

Goodwill and Other Intangible A

Goodwill and Other Intangible Assets	12 Months Ended
	Dec. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangible Assets	4. Goodwill and Other Intangible Assets The changes in gross carrying amounts of goodwill are as follows (in thousands): Goodwill December 31, 2013 $ 5,231 No Activity — December 31, 2014 5,231 Goodwill acquired 6,794 December 31, 2015 $ 12,025 The Company assesses goodwill for impairment on an annual basis in the fourth quarter, or more frequently if events or changes in circumstances indicate that the asset might be impaired. The Company reviews other intangible assets, including customer relationships and non-compete agreements, for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of long-lived assets is measured by a comparison of the carrying amount of the asset group to the future undiscounted net cash flows expected to be generated by those assets. If such assets are considered to be impaired, the impairment charge recognized is the amount by which the carrying amounts of the assets exceeds the fair value of the assets. The gross amounts and accumulated amortization of identifiable intangible assets are as follows (in thousands): December 31, 2015 December 31, 2014 Gross Amount Accumulated Amortization Gross Amount Accumulated Amortization Amortizable intangible assets: Customer relationships (useful life of 6-15 years) $ 19,000 $ 6,086 $ 7,700 $ 4,795 Covenants not-to-compete (useful life of 4-6 years) 4,425 3,786 3,625 3,587 Trademarks (useful life of 15 years) 1,500 92 — — Total $ 24,925 $ 9,964 $ 11,325 $ 8,382 Amortization expense for intangible assets was $1.6 million for 2015 and $0.6 million for 2014 and 2013. Estimated amortization expense for the five succeeding years follows (in thousands): Amount 2016 $ 1,668 2017 1,371 2018 1,363 2019 1,180 2020 1,163 Total $ 6,745

Computation of Earnings Per Sha

Computation of Earnings Per Share	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Computation of Earnings Per Share	5. Computation of Earnings Per Share The calculation of basic earnings per common share and diluted earnings per common share is as follows (in thousands except per share amounts): For The Years Ended December 31, 2015 2014 2013 Numerator: Net income $ 55,016 $ 51,991 $ 43,627 Denominator: Denominator for basic earnings per share–weighted average common shares 24,919 24,505 24,154 Effect of dilutive stock options 93 239 297 Effect of other common stock equivalents 459 719 754 Denominator for diluted earnings per share–adjusted weighted average common shares 25,471 25,463 25,205 Basic Earnings Per Share $ 2.21 $ 2.12 $ 1.81 Diluted Earnings Per Share $ 2.16 $ 2.04 $ 1.73 In 2015 and 2014, options and restricted stock for 206,756, and 7,936 shares of common stock, respectively, were excluded from the calculation of diluted earnings per share because their effect was anti-dilutive.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Stockholders' Equity	6. Stockholders’ Equity Share and per share amounts have been retroactively restated to reflect the three-for-two common stock split affected in 2013. Deferred Compensation Trust The Saia Executive Capital Accumulation Plan (the Capital Accumulation Plan) allows plan participants to make an irrevocable election to invest in the Company’s common stock. Upon distribution, the funds invested in the Company’s common stock will be paid out in Company stock rather than cash. The following table summarizes the shares of the Company’s common stock that were purchased and sold by the Company’s Rabbi Trust, which holds the investments for the Capital Accumulation Plan: Years ended December 31, 2015 2014 2013 Shares of common stock purchased 56,325 1,400 5,900 Aggregate purchase price of shares purchased $ 2,226,675 $ 52,961 $ 158,060 Shares of common stock sold 83,961 9,729 11,719 Aggregate sale price of shares sold $ 3,380,448 $ 53,962 $ 158,060 Since the Capital Accumulation Plan provides for the obligation to be settled only in Company stock, the deferred compensation obligation is classified as an equity instrument with no adjustments to operating results based on changes in fair value. Directors’ Deferred Compensation Under the Company’s Directors’ Deferred Fee Plan, non-employee directors may defer all or a portion of their annual fees and retainers which are otherwise payable. Such deferrals are converted into units equivalent to the value of the Company’s stock. Upon the director’s termination, death or disability, accumulated deferrals are distributed in the form of Company common stock. The Company has 229,679 and 244,835 shares reserved for issuance under the Directors’ Deferred Fee Plan at December 31, 2015 and 2014, respectively. The shares reserved for issuance under the Directors’ Deferred Fee Plan are treated as common stock equivalents in computing diluted earnings per share.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	7. Stock-Based Compensation ASC 718 requires the benefits of tax deductions in excess of recognized compensation cost to be reported as a financing cash flow, rather than as an operating cash flow. This requirement reduces net operating cash flows and increases net financing cash flows. For the years ended December 31, 2015, 2014 and 2013, cash flows from financing activities were increased by $3.7 million, $4.0 million, and $2.1 million, respectively, for such excess tax deductions. The stockholders of the Company approved the First Amended and Restated 2011 Omnibus Incentive Plan (the 2011 Omnibus Plan) and Amended and Restated 2003 Omnibus Incentive Plan (the 2003 Omnibus Plan) to allow the Company to issue equity based compensation to help attract and retain executive, managerial, supervisory or professional employees and non-employee directors. The 2011 Omnibus Plan has a total of 2,025,000 shares reserved. The Company had reserved 1,236,000 shares of its common stock under the 2003 Omnibus Plan. Following stockholder approval of the 2011 Omnibus Plan, no additional grants have been made under the 2003 Omnibus Plan and by the terms of the Plan, no new grants may be made after January 22, 2013. The 2011 Omnibus Plan and the 2003 Omnibus Plan provide for the grant or award of stock options; stock appreciation rights; restricted and unrestricted stock; and performance unit awards. Stock option awards are granted with an exercise price equal to the market price of the Company’s stock at the date of grant; stock option awards granted to employees under the plans to date have cliff vesting at the end of three years of continuous service and have a seven-year contractual term. The non-employee director stock options issued under the 2003 Omnibus Plan expire ten years from the date of grant; are exercisable six months after the date of grant; and have an exercise price equal to the fair market value of the Company’s common stock on the date of grant. No stock options have been granted to non-employee directors under the 2011 Omnibus Plan. The 2011 Omnibus Plan provides for an annual grant to each non-employee director of no more than 12,000 shares with the exact number of shares granted each year determined by the Compensation Committee of the Board. These share awards vest over three years subject to acceleration of vesting upon leaving the Board (other than for cause) or a change in control. Shares issued to each non-employee director under this provision were 2,093, 1,905, and 2,199 for the years ended December 31, 2015, 2014 and 2013, respectively. Non-employee directors were also issued 17,969, 16,561 and 24,191 units equivalent to shares in the Company’s common stock under the Directors’ Deferred Fee Plan during the years ended December 31, 2015, 2014 and 2013, respectively. At December 31, 2015 and 2014, no shares remain reserved and unissued under the provisions of the 2003 Omnibus Plan, as they are all allocated to outstanding Performance Unit Awards and outstanding stock options described below. At December 31, 2015 and 2014, 863,472 and 1,257,996 shares, respectively, remain reserved and unissued under the provisions of the 2011 Omnibus Plan, a portion of which are allocated to outstanding Performance Unit Awards, outstanding stock options and restricted stock described below. The Company has historically issued new shares to satisfy stock option exercises or other awards issued under the 2011 Omnibus Plan and 2003 Omnibus Plan. The years ended December 31, 2015, 2014 and 2013 had stock option and restricted stock compensation expense of $1.8 million, $2.2 million and $1.2 million, respectively, included in salaries, wages and employees’ benefits. The Company recognized a tax benefit consistent with the appropriate tax rates for each of the respective periods. As of December 31, 2015, there is unrecognized compensation expense of $2.2 million related to unvested stock options and restricted stock, which is expected to be recognized over a weighted average period of 2.0 years. The following table summarizes the activity of stock options for the year ended December 31, 2015 for both employees and non-employee directors: Options Weighted average exercise price Weighted Average Remaining Contractual Life (years) Aggregate Intrinsic Value (000’s) Outstanding at December 31, 2014 359,375 $ 22.03 Granted 117,600 Exercised (118,090 ) Forfeited (5,360 ) Expired — Outstanding at December 31, 2015 353,525 $ 31.63 4.7 $ 427 Exercisable at December 31, 2015 58,110 $ 18.53 2.1 $ 427 The total intrinsic value of options exercised during the years ended December 31, 2015, 2014 and 2013 was $3.5 million, $9.9 million, and $4.7 million, respectively. The weighted-average grant-date fair value per share of options granted during the years ended December 31, 2015, 2014 and 2013 was $15.41, $12.12, and $12.95, respectively. The weighted-average grant-date fair value per share of options vested during the years ended December 31, 2015, 2014 and 2013 was $5.66, $6.75, and $4.15, respectively. The following table summarizes the weighted average assumptions used in valuing options for the years ended December 31, 2015, 2014 and 2013: 2015 2014 2013 Risk free interest rate 1.54 % 1.58 % 0.80 % Expected life in years 4.5 4.5 4.5 Expected volatility 40.82 % 44.33 % 58.50 % Dividend rate — — — The risk-free rate for periods within the contractual life of the option is based on the U.S. Treasury yield in effect at the time of grant. The expected life of the options represents the period of time that options granted are expected to be outstanding. Expected volatilities are based on historical volatility of the Company’s stock. The following table summarizes the status of the Company’s unvested options as of December 31, 2015 and changes during the year ended December 31, 2015: Options Weighted average Grant-date Fair Value Unvested at December 31, 2014 359,375 $ 9.82 Granted 117,600 15.41 Vested (176,200 ) 5.66 Forfeited (5,360 ) 15.41 Unvested at December 31, 2015 295,415 $ 13.59 The Company granted shares of restricted stock to certain key executives in February 2013, September 2014 and May 2015. All of the outstanding shares of restricted stock issued vest 25% after three years, 25% after four years and the remaining 50% after five years assuming the executive has been in continuous service to the Company since the award date. The value of restricted stock is based on the fair market value of the Company’s common stock at the date of grant. The following table summarizes restricted stock activity during the year ended December 31, 2015: Shares Weighted average Grant-date Fair Value Restricted Stock at December 31, 2014 107,939 $ 13.90 Granted 3,651 $ 41.08 Vested (45,455 ) $ 11.00 Forfeited — — Restricted Stock at December 31, 2015 66,135 $ 17.39 Performance Unit Awards Under the 2011 Omnibus Plan and the 2003 Omnibus Plan, the Compensation Committee of the Board of Directors approved performance unit awards to a group of less than 20 management and executive employees. The criteria for payout of the awards is based on a comparison over the three-year performance period of these awards of the total shareholder return (TSR) of the Company’s common stock compared to the TSR of the companies in the peer group established by the Compensation Committee. The stock-based awards are accounted for in accordance with ASC 718 with the expense amortized over the three-year vesting period based on the fair value using the Monte Carlo method at the date the awards are granted. Operating results from continuing operations include expense for the performance unit awards of $1.2 million in 2015, $1.2 million in 2014 and $1.0 million in 2013. Shares earned under the performance unit awards will be issued in the first quarter of the year following the end of the performance period. There was an issuance of 49,983 shares for the January 2013-January 2016 performance period in February 2016, 146,054 shares for the January 2012-December 2014 performance period in February 2015, and 106,330 shares for the February 2011-February 2014 performance period in February 2014. The issuance of shares related to these awards would range from zero to a maximum of 66,316 shares per year as of December 31, 2015.

Employee Benefits

Employee Benefits	12 Months Ended
	Dec. 31, 2015
Compensation And Retirement Disclosure [Abstract]
Employee Benefits	8. Employee Benefits Defined Contribution Plans The Company sponsors defined contribution plans. The plans principally consist of contributory 401(k) savings plans and noncontributory profit sharing plans. The Company’s contributions to the 401(k) savings plans consist of a matching percentage. The Company match has historically been 50 percent of the first six percent of an eligible employee’s contributions. The Company elected to temporarily suspend the Company match in February 2009. Effective April 1, 2011, the Company reinstated one-half of the 401(k) match with the remainder of the match reinstated on December 1, 2013. The Company’s total contributions included in continuing operations for the years ended December 31, 2015, 2014 and 2013, were $6.4 million, $5.7 million, and $2.5 million, respectively. Deferred Compensation Plan The Capital Accumulation Plan is a nonqualified deferred compensation plan for Saia executives. The Capital Accumulation Plan allows for the plan participants to invest in the Company’s common stock. Elections to invest in the Company’s common stock are irrevocable and upon distribution, the funds invested in the Company’s common stock will be paid out in Company stock rather than cash. At December 31, 2015 and 2014, the Company’s Rabbi Trust, which holds the investments for the Capital Accumulation Plan, held 165,971 and 193,607 shares of the Company’s common stock, respectively, all of which were purchased on the open market. The shares held by the Capital Accumulation Plan are treated similar to treasury shares and deducted from basic shares outstanding for purposes of calculating basic earnings per share. However, because the distributions are required to be made in Company stock, these shares are added back to basic shares outstanding for the purposes of calculating diluted earnings per share. Annual Incentive Awards The Company provides annual cash performance incentive awards to salaried employees which are based primarily on actual operating results achieved, compared to targeted operating results. Operating results from continuing operations include performance incentive accruals of $2.9 million, $6.5 million, and $8.8 million in 2015, 2014 and 2013, respectively. Performance incentive awards for a year are primarily paid in the first quarter of the following year. Employee Stock Purchase Plan In January 2003, the Company adopted the Employee Stock Purchase Plan of Saia, Inc. (ESPP) allowing all eligible employees to purchase common stock of the Company at current market prices through payroll deductions of up to 10 percent of annual wages. In 2015, the Company amended the ESPP to allow highly compensated employees as defined by Section 401(a)(17) of the Internal Revenue Code to do payroll deductions of up to 20 percent of annual wages. The custodian uses the funds to purchase the Company’s common stock at current market prices. The custodian purchased 7,327, 4,751, and 6,711 shares in the open market during 2015, 2014 and 2013, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	9. Income Taxes Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Deferred tax liabilities (assets) are comprised of the following at December 31 (in thousands): 2015 2014 Depreciation $ 103,471 $ 100,607 Other 3,482 (559 ) Gross deferred tax liabilities 106,953 100,048 Allowance for doubtful accounts (1,350 ) (1,511 ) Equity-based compensation (3,961 ) (3,440 ) Employee benefits (4,847 ) (7,024 ) Claims and insurance (20,942 ) (22,019 ) Other (8,436 ) (7,108 ) Gross deferred tax assets (39,536 ) (41,102 ) Net deferred tax liability $ 67,417 $ 58,946 The Company has determined that a valuation allowance related to deferred tax assets was not necessary at December 31, 2015 or 2014 since it is more likely than not the deferred tax assets will be realized from future reversals of temporary differences or future taxable income. The income tax provision (benefit) for continuing operations consists of the following (in thousands): 2015 2014 2013 Current: U.S. federal $ 20,768 $ 18,085 $ 9,924 State 1,759 1,690 2,496 Total current income tax provision 22,527 19,775 12,420 Deferred: U.S. federal 8,570 9,547 11,822 State (150 ) (85 ) 276 Total deferred income tax provision 8,420 9,462 12,098 Total income tax provision $ 30,947 $ 29,237 $ 24,518 A reconciliation between income taxes at the federal statutory rate (35 percent) and the effective income tax provision is as follows (in thousands): 2015 2014 2013 Provision at federal statutory rate $ 30,087 $ 28,430 $ 23,851 State income taxes, net 2,229 2,426 2,574 Nondeductible business expenses 696 589 675 Tax credits (1,532 ) (1,434 ) (2,429 ) Other, net (533 ) (774 ) (153 ) Total provision $ 30,947 $ 29,237 $ 24,518 The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction and various state jurisdictions. For the U.S. federal jurisdiction, tax years 2013-2015 remain open to examination. The expiration of the statute of limitations related to the various state income tax returns that the Company files vary by state. In general, tax years 2006-2015 remain open to examination by the various state and local jurisdictions. However, a state could challenge certain tax positions back to the 2002 tax year. A reconciliation of the beginning and ending total amounts of gross unrecognized tax benefits is as follows (in thousands): 2015 2014 Gross unrecognized tax benefits at beginning of year $ 1,165 $ 1,281 Gross decreases in tax positions for prior years — — Gross increases in tax positions for current year 237 202 Settlements — — Lapse of statute of limitations (244 ) (318 ) Gross unrecognized tax benefits at end of year $ 1,158 $ 1,165 The Company recognizes interest and penalties related to uncertain tax positions as a component of income tax expense. During the years ended December 31, 2015, 2014 and 2013, respectively, the Company recorded interest related to unrecognized tax benefits of approximately $0.2 million, $0.3 million, and $0.1 million, respectively. The Company had approximately $1.0 million and $1.3 million of accrued interest and penalties at December 31, 2015 and 2014, respectively. The total amount of unrecognized tax benefits that would affect the Company’s effective tax rate if recognized is $1.2 million as of December 31, 2015 and 2014. The Company paid cash for income taxes of $16.4 million, $20.8 million, and $20.6 million in 2015, 2014 and 2013, respectively. The Company does not anticipate total unrecognized tax benefits will significantly change during the next twelve months due to the settlements of audits and the expiration of statutes of limitations. As a result of legislation enacted in 2015 and 2014, the Company recognized tax credits for alternative fuel usage of approximately $1.0 million in the fourth quarter of each year.

Summary of Quarterly Operating

Summary of Quarterly Operating Results (unaudited)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Summary of Quarterly Operating Results (unaudited)	10. Summary of Quarterly Operating Results (unaudited) (Amounts in thousands, except per share data) Three months ended, 2015 March 31 June 30 September 30 December 31 Operating revenue $ 293,022 $ 323,480 $ 317,199 $ 287,610 Operating income 21,233 31,281 19,845 17,616 Net income 12,605 19,247 11,777 11,387 Basic earnings per share $ 0.51 $ 0.77 $ 0.47 $ 0.46 Diluted earnings per share $ 0.49 $ 0.75 $ 0.46 $ 0.46 Three months ended, 2014 March 31 June 30 September 30 December 31 Operating revenue $ 299,730 $ 330,399 $ 332,544 $ 309,648 Operating income 15,231 22,741 27,149 20,572 Net income 8,576 13,568 16,278 13,569 Basic earnings per share $ 0.35 $ 0.55 $ 0.66 $ 0.55 Diluted earnings per share $ 0.34 $ 0.53 $ 0.64 $ 0.53

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Acquisition	11. Acquisition On February 2, 2015, the Company acquired 100% of the interests of LinkEx, an asset-light third party logistics business based in Dallas, Texas. The Company believes this acquisition is a future growth opportunity for its portfolio of services in the asset-light market. This acquisition fits into the Company’s strategic goal of diversifying Saia’s portfolio of service offerings. Pursuant to the terms of the purchase agreement, the Company paid $22.2 million at the acquisition date with a potential earn-out of up to $3 million subject to meeting profit targets. The Company concluded that LinkEx will not likely meet these profit targets and, thus, has not recorded a liability related to contingent consideration as of the acquisition date. During the fourth quarter of 2015, the Company finalized its purchase accounting related to the acquisition of LinkEx, Inc. as indicated below (in thousands). The goodwill, customer lists and other identifiable intangible assets associated with the acquisition will be deductible for federal and state income tax purposes ratably over a 15 year period. The weighted-average useful life for the identified intangible assets is 14.4 years. Consideration: Cash, net of cash received $ (22,238 ) Fair value of total consideration transferred $ (22,238 ) Acquisition related costs included in SG&A 300 Recognized amounts of identifiable assets acquired and liabilities assumed: Current assets $ 4,337 Property and equipment 430 Customer lists 11,300 Other identifiable intangible assets 2,300 Other non-current assets 9 Current liabilities (2,900 ) Non-current liabilities (32 ) Total identifiable net assets assumed $ 15,444 Goodwill 6,794 Total $ 22,238 Results of LinkEx are included in the accompanying Consolidated Statements of Operations commencing on the date of acquisition. The Company accounted for the acquisition using the acquisition method of accounting, which requires, among other things, that the assets acquired and liabilities assumed be recognized at the acquisition date fair values, with any excess of the consideration transferred over the estimated fair values of the identifiable net assets acquired recorded as goodwill. Goodwill is an asset representing operational synergies and future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2015
Valuation And Qualifying Accounts [Abstract]
Valuation and Qualifying Accounts	12. Valuation and Qualifying Accounts For the Years Ended December 31, 2015, 2014 and 2013 (in thousands) Additions Balance, beginning of period Charged to costs and expenses Charged to other accounts Deductions(1) Balance, end of period Year ended December 31, 2015: Deducted from asset account – Allowance for uncollectible accounts $ 3,868 $ 1,463 — $ (1,880 ) $ 3,451 Year ended December 31, 2014: Deducted from asset account – Allowance for uncollectible accounts 3,737 1,942 — (1,811 ) 3,868 Year ended December 31, 2013: Deducted from asset account – Allowance for uncollectible accounts 3,881 2,227 — (2,371 ) 3,737 (1) Primarily uncollectible accounts written off — net of recoveries.

Description of Business and S20

Description of Business and Summary of Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Description of Business	Description of Business Saia, Inc. and its subsidiaries (Saia or the Company) are headquartered in Johns Creek, Georgia. The Company offers customers a wide range of less-than-truckload, non-asset truckload, expedited and logistics services across the United States through its wholly-owned subsidiaries. Effective December 31, 2015, the Company’s subsidiaries were as follows: Saia Motor Freight Line, LLC, doing business as Saia LTL Freight; Saia TL Plus, LLC, formerly Robart Transportation, Inc.; Saia Sales, LLC; Saia Logistics Services, LLC, formerly The RL Services Group, LLC; MetroGo, LLC., formed on January 22, 2015; and LinkEx, Inc. acquired on February 2, 2015. The Chief Operating Decision Maker is the Chief Executive Officer who manages the business, regularly reviews financial information and allocates resources. The Company has one operating segment.
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of Saia, Inc. and its wholly-owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in the consolidated financial statements.
Common Stock Split	Common Stock Split On May 16, 2013, the Company announced a three-for-two stock split in the form of a 50 percent stock dividend. The shares were distributed on June 13, 2013 to shareholders of record as of the close of business on the record date of May 31, 2013. In lieu of fractional shares, shareholders received a cash payment based on the closing share price of the Company’s common stock on the record date. All references in this report to common shares outstanding, weighted average common shares and earnings per share amounts have been retroactively restated to reflect this stock split.
Use of Estimates	Use of Estimates Management makes estimates and assumptions when preparing the consolidated financial statements in conformity with U.S. generally accepted accounting principles. These estimates and assumptions affect the amounts reported in the consolidated financial statements and footnotes. Actual results could differ from those estimates.
Accounting Pronouncements Adopted During 2015	Accounting Pronouncements Adopted During 2015 In April 2015, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2015-03, Interest – Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs In November 2015, the FASB issued ASU 2015-17, Income Taxes (Subtopic 740): Balance Sheet Classification of Deferred Taxes
Accounting Pronouncements Not Yet Adopted	Accounting Pronouncements Not Yet Adopted In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers,
Cash and Cash Equivalents and Checks Outstanding	Cash and Cash Equivalents and Checks Outstanding: Cash and cash equivalents in excess of current operating requirements are invested in short-term interest bearing instruments purchased with original maturities of three months or less and are stated at cost, which approximates market. Checks outstanding in excess of cash on deposit are classified in accounts payable on the accompanying consolidated balance sheets and in operating activities in the accompanying consolidated statements of cash flows.
Inventories, fuel and operating supplies	Inventories, fuel and operating supplies: Inventories are carried at average cost and included in other current assets. To mitigate the Company’s risk to rising fuel prices, the Company has implemented fuel surcharge programs and considers effects of these fuel surcharge programs in customer pricing negotiations.
Property and Equipment Including Repairs and Maintenance	Property and Equipment Including Repairs and Maintenance: Property and equipment are carried at cost less accumulated depreciation. Depreciation is computed using the straight-line method based on the following service lives: Years Structures 20 to 25 Tractors 6 to 10 Trailers 10 to 14 Other revenue equipment 10 to 14 Technology equipment and software 3 to 5 Other 3 to 10 At December 31, property and equipment consisted of the following (in thousands): 2015 2014 Land $ 57,506 $ 53,632 Structures 181,769 140,206 Tractors 314,326 290,718 Trailers 256,494 237,262 Other revenue equipment 36,828 37,220 Technology equipment and software 72,707 63,773 Other 75,884 68,334 Total property and equipment, at cost $ 995,514 $ 891,145 Maintenance and repairs are charged to operations while replacements and improvements that extend the asset’s life are capitalized. The Company’s investment in technology equipment and software consists primarily of systems to support customer service and freight management. Depreciation was $63.4 million, $58.4 million and $51.0 million for the years ended December 31, 2015, 2014 and 2013, respectively. Depreciation and amortization expense includes amortization of assets under capital lease.
Computer Software Developed or Obtained for Internal Use	Computer Software Developed or Obtained for Internal Use: The Company capitalizes certain costs associated with developing or obtaining internal-use software. Capitalizable costs include external direct costs of materials and services utilized in developing or obtaining the software and payroll and payroll-related costs for employees directly associated with the development of the project. For the years ended December 31, 2015, 2014, and 2013, the Company capitalized $2.2 million, $1.0 million, and $2.1 million, respectively, of primarily payroll-related costs.
Claims and Insurance Accruals	Claims and Insurance Accruals: Claims and insurance accruals, both current and long-term, reflect the estimated cost of claims for workers’ compensation (discounted to present value), cargo loss and damage, and bodily injury and property damage not covered by insurance. These costs are included in claims and insurance expense, except for workers’ compensation, which is included in employees’ benefits expense. The liabilities for self-funded retention are included in claims and insurance reserves based on claims incurred. Liabilities for unsettled claims and claims incurred but not yet reported are actuarially determined with respect to workers’ compensation claims and with respect to all other liabilities, estimated based on management’s evaluation of the nature and severity of individual claims and past experience. The former parent of Saia provides guarantees for claims in certain self-insured states that arose prior to September 30, 2002 (See Note 3 for more information regarding the guarantees). Risk retention amounts per occurrence during the three years ended December 31, 2015, were as follows: Workers’ compensation $ 1,000,000 Bodily injury and property damage 2,000,000 Employee medical and hospitalization 350,000 Cargo loss and damage 250,000 The Company’s insurance accruals are presented net of amounts receivable from insurance companies that provide coverage above the Company’s retention.
Income Taxes	Income Taxes: Income taxes are accounted for under the asset and liability method. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carry forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. As required by FASB Accounting Standards Codification (“ASC”) 740, , the Company follows this guidance which defines the threshold for recognizing the benefits of tax-filing positions in the financial statements as “more-likely-than-not” to be sustained by the tax authority. ASC 740 also prescribes a method for computing the tax benefit of such tax positions to be recognized in the financial statements. In addition, it provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosure and transition.
Revenue Recognition	Revenue Recognition: Revenue is recognized on a percentage-of-completion basis for shipments in transit while expenses are recognized as incurred. Logistics services engage in some transactions wherein they act as agents. Revenue from these transactions is recorded on a net basis. Net revenue includes billings to customers less third-party charges.
Stock-Based Compensation	Stock-Based Compensation: The Company accounts for its employee stock-based compensation awards in accordance with ASC 718, . ASC 718 requires that all employee stock-based compensation is recognized as an expense in the financial statements and that for equity-classified awards such expenses are measured at the grant date fair value of the award. Stock options are accounted for in accordance with ASC 718 with the expense amortized over the three-year vesting period using a Black-Sholes-Merton model to estimate the fair value of stock options granted to employees. Stock-based performance unit awards are accounted for in accordance with ASC 718 with the expense amortized over the three-year vesting period using a Monte Carlo model to estimate fair value at the date the awards are granted.
Credit Risk	Credit Risk: The Company routinely grants credit to its customers. The risk of significant loss in trade receivables is substantially mitigated by the Company’s credit evaluation process, short collection terms, low revenue per transaction and services performed for a large number of customers with no single customer representing more than 6.0 percent of consolidated operating revenue. Allowances for potential credit losses are based on historical loss experience, current economic environment, expected trends and customer specific factors.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets: As required by ASC 360, , long-lived assets, such as property, plant and equipment, and purchased intangible assets subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require a long-lived asset or asset group be tested for possible impairment, the Company first compares undiscounted cash flows expected to be generated by that asset or asset group to its carrying value. If the carrying value of the long-lived asset or asset group is not recoverable on an undiscounted cash flow basis, impairment is recognized to the extent that the carrying value exceeds its fair value. Fair value is determined through various valuation techniques including discounted cash flow models, quoted market values and third-party independent appraisals, as deemed necessary. The Company has adopted ASU 2011-08, Testing Goodwill for Impairment Intangibles – Goodwill and Other
Advertising	Advertising: The costs of advertising are expensed as incurred. Advertising costs charged to expense were $ 1.7 million, $1.9 million, and $0.8 million in 2015, 2014 and 2013, respectively.
Financial Instruments	Financial Instruments The carrying amounts of financial instruments including cash and cash equivalents, accounts receivable, accounts payable and short-term debt approximated fair value as of December 31, 2015 and 2014, because of the relatively short maturity of these instruments. See Note 2 for fair value disclosures related to long-term debt.

Description of Business and S21

Description of Business and Summary of Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Summary of Property and Equipment, Estimated Useful Lives	Depreciation is computed using the straight-line method based on the following service lives: Years Structures 20 to 25 Tractors 6 to 10 Trailers 10 to 14 Other revenue equipment 10 to 14 Technology equipment and software 3 to 5 Other 3 to 10
Schedule of Property and Equipment	At December 31, property and equipment consisted of the following (in thousands): 2015 2014 Land $ 57,506 $ 53,632 Structures 181,769 140,206 Tractors 314,326 290,718 Trailers 256,494 237,262 Other revenue equipment 36,828 37,220 Technology equipment and software 72,707 63,773 Other 75,884 68,334 Total property and equipment, at cost $ 995,514 $ 891,145
Summary of Risk Retention Amounts Per Occurrence	Risk retention amounts per occurrence during the three years ended December 31, 2015, were as follows: Workers’ compensation $ 1,000,000 Bodily injury and property damage 2,000,000 Employee medical and hospitalization 350,000 Cargo loss and damage 250,000

Debt and Financing Arrangemen22

Debt and Financing Arrangements (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Summary of Reconciliation of Debt	At December 31, debt consisted of the following (in thousands): December 31, 2015 December 31, 2014 Credit Agreement with Banks, described below $ 14,534 $ 45,000 Senior Notes under a Master Shelf Agreement, described below 14,286 21,429 Capital Leases, described below 40,152 16,606 Total debt 68,972 83,035 Less: current portion of long-term debt 12,432 9,138 Long-term debt, less current portion $ 56,540 $ 73,897
Schedule of Principal Maturities of Long-Term Debt	The principal maturities of long-term debt for the next five years (in thousands) are as follows: Amount 2016 $ 13,508 2017 13,508 2018 6,365 2019 6,365 2020 20,899 Thereafter 12,449 Total 73,094 Less: Amounts Representing Interest on Capital Leases 4,122 Total $ 68,972

Commitments, Contingencies an23

Commitments, Contingencies and Uncertainties (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments And Contingencies Disclosure [Abstract]
Schedule of Non-Cancellable Capital And Operating Lease Agreements Requiring Minimum Annual Rentals Payable	At December 31, 2015, the Company was committed under non-cancellable operating lease agreements requiring minimum annual rentals payable as follows (in thousands): Amount 2016 $ 14,232 2017 12,646 2018 10,088 2019 7,488 2020 4,875 Thereafter 12,513 Total $ 61,842

Goodwill and Other Intangible24

Goodwill and Other Intangible Assets (Tables)	12 Months Ended
	Dec. 31, 2015
Goodwill And Intangible Assets Disclosure [Abstract]
Summary of Changes in Gross Carrying Amounts of Goodwill	The changes in gross carrying amounts of goodwill are as follows (in thousands): Goodwill December 31, 2013 $ 5,231 No Activity — December 31, 2014 5,231 Goodwill acquired 6,794 December 31, 2015 $ 12,025
Summary of Gross Amounts and Accumulated Amortization of Identifiable Intangible Assets	The gross amounts and accumulated amortization of identifiable intangible assets are as follows (in thousands): December 31, 2015 December 31, 2014 Gross Amount Accumulated Amortization Gross Amount Accumulated Amortization Amortizable intangible assets: Customer relationships (useful life of 6-15 years) $ 19,000 $ 6,086 $ 7,700 $ 4,795 Covenants not-to-compete (useful life of 4-6 years) 4,425 3,786 3,625 3,587 Trademarks (useful life of 15 years) 1,500 92 — — Total $ 24,925 $ 9,964 $ 11,325 $ 8,382
Summary of Estimated Amortization Expense	Estimated amortization expense for the five succeeding years follows (in thousands): Amount 2016 $ 1,668 2017 1,371 2018 1,363 2019 1,180 2020 1,163 Total $ 6,745

Computation of Earnings Per S25

Computation of Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Summary of Calculation of Basic Earnings Per Common Share and Diluted Earnings Per Common Share	The calculation of basic earnings per common share and diluted earnings per common share is as follows (in thousands except per share amounts): For The Years Ended December 31, 2015 2014 2013 Numerator: Net income $ 55,016 $ 51,991 $ 43,627 Denominator: Denominator for basic earnings per share–weighted average common shares 24,919 24,505 24,154 Effect of dilutive stock options 93 239 297 Effect of other common stock equivalents 459 719 754 Denominator for diluted earnings per share–adjusted weighted average common shares 25,471 25,463 25,205 Basic Earnings Per Share $ 2.21 $ 2.12 $ 1.81 Diluted Earnings Per Share $ 2.16 $ 2.04 $ 1.73

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2015
Equity [Abstract]
Summary of Purchase and Sale of Common Stock	The following table summarizes the shares of the Company’s common stock that were purchased and sold by the Company’s Rabbi Trust, which holds the investments for the Capital Accumulation Plan: Years ended December 31, 2015 2014 2013 Shares of common stock purchased 56,325 1,400 5,900 Aggregate purchase price of shares purchased $ 2,226,675 $ 52,961 $ 158,060 Shares of common stock sold 83,961 9,729 11,719 Aggregate sale price of shares sold $ 3,380,448 $ 53,962 $ 158,060

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Option Activity	The following table summarizes the activity of stock options for the year ended December 31, 2015 for both employees and non-employee directors: Options Weighted average exercise price Weighted Average Remaining Contractual Life (years) Aggregate Intrinsic Value (000’s) Outstanding at December 31, 2014 359,375 $ 22.03 Granted 117,600 Exercised (118,090 ) Forfeited (5,360 ) Expired — Outstanding at December 31, 2015 353,525 $ 31.63 4.7 $ 427 Exercisable at December 31, 2015 58,110 $ 18.53 2.1 $ 427
Summary of Weighted Average Assumptions Used In Valuing Options	The following table summarizes the weighted average assumptions used in valuing options for the years ended December 31, 2015, 2014 and 2013: 2015 2014 2013 Risk free interest rate 1.54 % 1.58 % 0.80 % Expected life in years 4.5 4.5 4.5 Expected volatility 40.82 % 44.33 % 58.50 % Dividend rate — — —
Summary of Unvested Option	The following table summarizes the status of the Company’s unvested options as of December 31, 2015 and changes during the year ended December 31, 2015: Options Weighted average Grant-date Fair Value Unvested at December 31, 2014 359,375 $ 9.82 Granted 117,600 15.41 Vested (176,200 ) 5.66 Forfeited (5,360 ) 15.41 Unvested at December 31, 2015 295,415 $ 13.59
Summary of Restricted Stock Activity	The Company granted shares of restricted stock to certain key executives in February 2013, September 2014 and May 2015. All of the outstanding shares of restricted stock issued vest 25% after three years, 25% after four years and the remaining 50% after five years assuming the executive has been in continuous service to the Company since the award date. The value of restricted stock is based on the fair market value of the Company’s common stock at the date of grant. The following table summarizes restricted stock activity during the year ended December 31, 2015: Shares Weighted average Grant-date Fair Value Restricted Stock at December 31, 2014 107,939 $ 13.90 Granted 3,651 $ 41.08 Vested (45,455 ) $ 11.00 Forfeited — — Restricted Stock at December 31, 2015 66,135 $ 17.39

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Summary of Deferred Tax Liabilities and Assets	Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Deferred tax liabilities (assets) are comprised of the following at December 31 (in thousands): 2015 2014 Depreciation $ 103,471 $ 100,607 Other 3,482 (559 ) Gross deferred tax liabilities 106,953 100,048 Allowance for doubtful accounts (1,350 ) (1,511 ) Equity-based compensation (3,961 ) (3,440 ) Employee benefits (4,847 ) (7,024 ) Claims and insurance (20,942 ) (22,019 ) Other (8,436 ) (7,108 ) Gross deferred tax assets (39,536 ) (41,102 ) Net deferred tax liability $ 67,417 $ 58,946
Summary of Income Tax Provision (Benefit)	The income tax provision (benefit) for continuing operations consists of the following (in thousands): 2015 2014 2013 Current: U.S. federal $ 20,768 $ 18,085 $ 9,924 State 1,759 1,690 2,496 Total current income tax provision 22,527 19,775 12,420 Deferred: U.S. federal 8,570 9,547 11,822 State (150 ) (85 ) 276 Total deferred income tax provision 8,420 9,462 12,098 Total income tax provision $ 30,947 $ 29,237 $ 24,518
Summary of Reconciliation Between Income Taxes and Effective Income Tax Provision	A reconciliation between income taxes at the federal statutory rate (35 percent) and the effective income tax provision is as follows (in thousands): 2015 2014 2013 Provision at federal statutory rate $ 30,087 $ 28,430 $ 23,851 State income taxes, net 2,229 2,426 2,574 Nondeductible business expenses 696 589 675 Tax credits (1,532 ) (1,434 ) (2,429 ) Other, net (533 ) (774 ) (153 ) Total provision $ 30,947 $ 29,237 $ 24,518
Summary of Gross Unrecognized Tax Benefits	A reconciliation of the beginning and ending total amounts of gross unrecognized tax benefits is as follows (in thousands): 2015 2014 Gross unrecognized tax benefits at beginning of year $ 1,165 $ 1,281 Gross decreases in tax positions for prior years — — Gross increases in tax positions for current year 237 202 Settlements — — Lapse of statute of limitations (244 ) (318 ) Gross unrecognized tax benefits at end of year $ 1,158 $ 1,165

Summary of Quarterly Operatin29

Summary of Quarterly Operating Results (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Summary of Quarterly Operating Results (Unaudited)	(Amounts in thousands, except per share data) Three months ended, 2015 March 31 June 30 September 30 December 31 Operating revenue $ 293,022 $ 323,480 $ 317,199 $ 287,610 Operating income 21,233 31,281 19,845 17,616 Net income 12,605 19,247 11,777 11,387 Basic earnings per share $ 0.51 $ 0.77 $ 0.47 $ 0.46 Diluted earnings per share $ 0.49 $ 0.75 $ 0.46 $ 0.46 Three months ended, 2014 March 31 June 30 September 30 December 31 Operating revenue $ 299,730 $ 330,399 $ 332,544 $ 309,648 Operating income 15,231 22,741 27,149 20,572 Net income 8,576 13,568 16,278 13,569 Basic earnings per share $ 0.35 $ 0.55 $ 0.66 $ 0.55 Diluted earnings per share $ 0.34 $ 0.53 $ 0.64 $ 0.53

Acquisition (Tables)

Acquisition (Tables)	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Summary of Cash Purchase Price Allocated Based on Independent Appraisals and Managements Estimates	During the fourth quarter of 2015, the Company finalized its purchase accounting related to the acquisition of LinkEx, Inc. as indicated below (in thousands). The goodwill, customer lists and other identifiable intangible assets associated with the acquisition will be deductible for federal and state income tax purposes ratably over a 15 year period. The weighted-average useful life for the identified intangible assets is 14.4 years. Consideration: Cash, net of cash received $ (22,238 ) Fair value of total consideration transferred $ (22,238 ) Acquisition related costs included in SG&A 300 Recognized amounts of identifiable assets acquired and liabilities assumed: Current assets $ 4,337 Property and equipment 430 Customer lists 11,300 Other identifiable intangible assets 2,300 Other non-current assets 9 Current liabilities (2,900 ) Non-current liabilities (32 ) Total identifiable net assets assumed $ 15,444 Goodwill 6,794 Total $ 22,238

Valuation and Qualifying Acco31

Valuation and Qualifying Accounts (Tables)	12 Months Ended
	Dec. 31, 2015
Valuation And Qualifying Accounts [Abstract]
Summary of Valuation and Qualifying Accounts	For the Years Ended December 31, 2015, 2014 and 2013 (in thousands) Additions Balance, beginning of period Charged to costs and expenses Charged to other accounts Deductions(1) Balance, end of period Year ended December 31, 2015: Deducted from asset account – Allowance for uncollectible accounts $ 3,868 $ 1,463 — $ (1,880 ) $ 3,451 Year ended December 31, 2014: Deducted from asset account – Allowance for uncollectible accounts 3,737 1,942 — (1,811 ) 3,868 Year ended December 31, 2013: Deducted from asset account – Allowance for uncollectible accounts 3,881 2,227 — (2,371 ) 3,737 (1) Primarily uncollectible accounts written off — net of recoveries.

Description of Business and S32

Description of Business and Summary of Accounting Policies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)SegmentCustomer	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	May. 16, 2013
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Number of reportable segment | Segment	1
Common stock dividend				50.00%
Common stock split	Three-for-two
Deferred tax assets reclassified to noncurrent liabilities	$ 19.5
Depreciation	63.4	$ 58.4	$ 51
Primary payroll-related costs capitalized	$ 2.2	1	2.1
Stock-based awards compensation expense amortization period	3 years
Number of customers | Customer	0
Percentage of consolidated operating revenue	6.00%
Advertising costs	$ 1.7	$ 1.9	$ 0.8

Description of Business and S33

Description of Business and Summary of Accounting Policies - Summary of Property and Equipment, Estimated Useful Lives (Detail)	12 Months Ended
	Dec. 31, 2015
Structures [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	20 years
Structures [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	25 years
Tractors [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	6 years
Tractors [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	10 years
Trailers [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	10 years
Trailers [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	14 years
Other Revenue Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	10 years
Other Revenue Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	14 years
Technology Equipment and Software [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	3 years
Technology Equipment and Software [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	5 years
Other [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	3 years
Other [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, service lives	10 years

Description of Business and S34

Description of Business and Summary of Accounting Policies - Schedule of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$ 995,514	$ 891,145
Land [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	57,506	53,632
Structures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	181,769	140,206
Tractors [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	314,326	290,718
Trailers [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	256,494	237,262
Other Revenue Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	36,828	37,220
Technology Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	72,707	63,773
Other [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, at cost	$ 75,884	$ 68,334

Description of Business and S35

Description of Business and Summary of Accounting Policies - Summary of Risk Retention Amounts Per Occurrence (Detail)	12 Months Ended
	Dec. 31, 2015USD ($)
Schedule Of Retention Amounts For Uninsured Claims Per Occurrence Basis [Abstract]
Workers’ compensation	$ 1,000,000
Bodily injury and property damage	2,000,000
Employee medical and hospitalization	350,000
Cargo loss and damage	$ 250,000

Debt and Financing Arrangemen36

Debt and Financing Arrangements - Summary of Reconciliation of Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Senior Notes under a Master Shelf Agreement	$ 14,286	$ 21,429
Capital Leases, described below	40,152	16,606
Total debt	68,972	83,035
Current portion of long-term debt	12,432	9,138
Long-term debt, less current portion	56,540	73,897
Credit Agreement with Banks [Member]
Debt Instrument [Line Items]
Credit Agreement with Banks	$ 14,534	$ 45,000

Debt and Financing Arrangemen37

Debt and Financing Arrangements - Additional Information (Detail) - USD ($)	Mar. 06, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jan. 31, 2008	Nov. 30, 2007	Apr. 30, 2005	Sep. 20, 2002
Debt Instrument [Line Items]
Capital Leases, described below		$ 40,152,000	$ 16,606,000
Lease expiration period		7 years
Cash paid for interest		$ 3,000,000	4,500,000	$ 6,100,000
Estimated fair value of total debt		$ 73,100,000	$ 83,700,000
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Weighted average interest rate for capital lease		2.85%	2.92%
Credit Agreement with Banks [Member]
Debt Instrument [Line Items]
Credit Agreement with Banks		$ 14,534,000	$ 45,000,000
Fifth Amended and Restated Credit Agreement [Member]
Debt Instrument [Line Items]
Amendment line of credit facility expiration year and month	2020-03
Fifth Amended and Restated Credit Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Borrowing capacity under credit agreement	$ 250,000,000
Fifth Amended and Restated Credit Agreement [Member] | Revolving Credit Facility [Member] | Credit Agreement Before Amendments [Member]
Debt Instrument [Line Items]
Borrowing capacity under credit agreement	$ 200,000,000
Restated Credit Agreement [Member]
Debt Instrument [Line Items]
Letter of credit facility outstanding amount		$ 44,800,000	47,300,000
Restated Credit Agreement [Member] | Minimum [Member]
Debt Instrument [Line Items]
Letter of credit unused portion fee		0.20%
Restated Credit Agreement [Member] | Maximum [Member]
Debt Instrument [Line Items]
Letter of credit unused portion fee		0.30%
Restated Credit Agreement [Member] | LIBOR Rate Margin [Member] | Minimum [Member]
Debt Instrument [Line Items]
Rate margin		1.125%
Restated Credit Agreement [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Borrowing capacity under credit agreement		$ 250,000,000
Line of credit facility expiration year and month		2020-03
Additional borrowing capacity under revolving credit facility		$ 75,000,000
Restated Credit Agreement [Member] | Credit Agreement with Banks [Member]
Debt Instrument [Line Items]
Credit Agreement with Banks		$ 14,500,000	$ 45,000,000
Restated Credit Agreement [Member] | Credit Agreement with Banks [Member] | Minimum [Member]
Debt Instrument [Line Items]
Rate margin		1.125%
Restated Credit Agreement [Member] | Credit Agreement with Banks [Member] | Maximum [Member]
Debt Instrument [Line Items]
Rate margin		2.25%
Restated Credit Agreement [Member] | Credit Agreement with Banks [Member] | LIBOR Rate Margin [Member] | Maximum [Member]
Debt Instrument [Line Items]
Rate margin		2.25%
Restated Credit Agreement [Member] | Credit Agreement with Banks [Member] | Base Rate Margin [Member] | Minimum [Member]
Debt Instrument [Line Items]
Rate margin		0.125%
Restated Credit Agreement [Member] | Credit Agreement with Banks [Member] | Base Rate Margin [Member] | Maximum [Member]
Debt Instrument [Line Items]
Rate margin		0.50%
Restated Master Shelf Agreement [Member] | Senior Notes under Master Shelf Agreement [Member]
Debt Instrument [Line Items]
Senior notes issued, value					$ 25,000,000	$ 25,000,000		$ 100,000,000
Senior notes authorized amount							$ 150,000,000	$ 125,000,000
Interest rate on notes					6.17%	6.14%		7.38%
Senior credit facility, Interest rate terms description		The initial $100 million Senior Notes had a fixed interest rate of 7.38 percent. Payments due under the $100 million Senior Notes were interest only until June 30, 2006 and at that time semi-annual principal payments began with the final payment made in December 2013. The November 2007 issuance of $25 million Senior Notes has a fixed interest rate of 6.14 percent. The January 2008 issuance of $25 million Senior Notes has a fixed interest rate of 6.17 percent. Payments due for both $25 million issuances were interest only until June 30, 2011 and at that time semi-annual principal payments began with the final payments due December 31, 2017.

Debt and Financing Arrangemen38

Debt and Financing Arrangements - Schedule of Principal Maturities of Long-Term Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
2,016	$ 13,508
2,017	13,508
2,018	6,365
2,019	6,365
2,020	20,899
Thereafter	12,449
Total	73,094
Total	68,972	$ 83,035
Capital Lease Obligations [Member]
Debt Instrument [Line Items]
Less: Amounts Representing Interest on Capital Leases	$ 4,122

Commitments, Contingencies an39

Commitments, Contingencies and Uncertainties - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Commitments [Line Items]
Rent expense	$ 17.9	$ 17.1	$ 17.9
Capital expenditures committed	24.7
Capital expenditures in accounts payable	12.1	1.8
Affiliated Entity [Member]
Other Commitments [Line Items]
Letters of Credit	$ 1.8	$ 1.8

Commitments, Contingencies an40

Commitments, Contingencies and Uncertainties - Schedule of Non-Cancellable Capital and Operating Lease Agreements Requiring Minimum Annual Rentals Payable (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,016	$ 14,232
2,017	12,646
2,018	10,088
2,019	7,488
2,020	4,875
Thereafter	12,513
Total	$ 61,842

Goodwill and Other Intangible41

Goodwill and Other Intangible Assets - Summary of Changes in Gross Carrying Amounts of Goodwill (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Goodwill Roll Forward
Goodwill, Beginning Balance	$ 5,231
Goodwill acquired	6,794
Goodwill, Ending Balance	$ 12,025

Goodwill and Other Intangible42

Goodwill and Other Intangible Assets - Summary of Gross Amounts and Accumulated Amortization of Identifiable Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Gross Amount	$ 24,925	$ 11,325
Accumulated Amortization	9,964	8,382
Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	19,000	7,700
Accumulated Amortization	6,086	4,795
Covenants not-to-Compete [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	4,425	3,625
Accumulated Amortization	3,786	$ 3,587
Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Gross Amount	1,500
Accumulated Amortization	$ 92

Goodwill and Other Intangible43

Goodwill and Other Intangible Assets - Summary of Gross Amounts and Accumulated Amortization of Identifiable Intangible Assets (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2015
Trademarks [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, useful life	15 years
Minimum [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, useful life	6 years
Minimum [Member] | Covenants not-to-Compete [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, useful life	4 years
Maximum [Member] | Customer Relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, useful life	15 years
Maximum [Member] | Covenants not-to-Compete [Member]
Finite-Lived Intangible Assets [Line Items]
Amortizable intangible assets, useful life	6 years

Goodwill and Other Intangible44

Goodwill and Other Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expense for intangible assets	$ 1.6	$ 0.6	$ 0.6

Goodwill and Other Intangible45

Goodwill and Other Intangible Assets - Summary of Estimated Amortization Expense (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Finite Lived Intangible Assets Future Amortization Expense [Abstract]
2,016	$ 1,668
2,017	1,371
2,018	1,363
2,019	1,180
2,020	1,163
Total	$ 6,745

Computation of Earnings Per S46

Computation of Earnings Per Share - Summary of Calculation of Basic Earnings Per Common Share and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net income	$ 11,387	$ 11,777	$ 19,247	$ 12,605	$ 13,569	$ 16,278	$ 13,568	$ 8,576	$ 55,016	$ 51,991	$ 43,627
Denominator:
Denominator for basic earnings per share–weighted average common shares									24,919	24,505	24,154
Effect of dilutive stock options									93	239	297
Effect of other common stock equivalents									459	719	754
Denominator for diluted earnings per share–adjusted weighted average common shares									25,471	25,463	25,205
Basic Earnings Per Share	$ 0.46	$ 0.47	$ 0.77	$ 0.51	$ 0.55	$ 0.66	$ 0.55	$ 0.35	$ 2.21	$ 2.12	$ 1.81
Diluted Earnings Per Share	$ 0.46	$ 0.46	$ 0.75	$ 0.49	$ 0.53	$ 0.64	$ 0.53	$ 0.34	$ 2.16	$ 2.04	$ 1.73

Computation of Earnings Per S47

Computation of Earnings Per Share - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Earnings Per Share [Abstract]
Common stock excluded from the calculation of diluted earnings per share	206,756	7,936

Stockholders' Equity - Summary

Stockholders' Equity - Summary of Purchase and Sale of Common Stock (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity [Abstract]
Shares of common stock purchased	56,325	1,400	5,900
Aggregate purchase price of shares purchased	$ 2,226,675	$ 52,961	$ 158,060
Shares of common stock sold	83,961	9,729	11,719
Aggregate sale price of shares sold	$ 3,380,448	$ 53,962	$ 158,060

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - shares	Dec. 31, 2015	Dec. 31, 2014
Equity [Abstract]
Shares reserved for issuance under the Directors Deferred Fee Plan	229,679	244,835

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)Employee$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Dec. 31, 2013USD ($)$ / sharesshares	Feb. 29, 2016shares	Feb. 28, 2015shares	Feb. 28, 2014shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in cash flows from financing activities | $	$ 3,700	$ 4,000	$ 2,100
Non-employee director stock options plan expiration period	10 years
Stock-based compensation | $	$ 3,878	4,166	2,902
Unrecognized compensation expense | $	$ 2,200
Weighted average recognition period of compensation expenses	2 years
Total intrinsic value of options exercised | $	$ 3,500	$ 9,900	$ 4,700
Weighted-average grant-date fair value per share of options granted | $ / shares	$ 15.41	$ 12.12	$ 12.95
Weighted-average grant-date fair value per share of options vested | $ / shares	$ 5.66	$ 6.75	$ 4.15
After three years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting percentage	25.00%
After four years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting percentage	25.00%
After five years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting percentage	50.00%
January 2013 - January 2016 [Member] | Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period share issuance range				49,983
December 2012 - December 2014 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period share issuance range					146,054
February 2011 - February 2014 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period share issuance range						106,330
Stock Option and Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation | $	$ 1,800	$ 2,200	$ 1,200
Restricted Stock [Member] | After three years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	3 years
Restricted Stock [Member] | After four years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	4 years
Restricted Stock [Member] | After five years [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	5 years
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock vesting period	3 years
Operating expense | $	$ 1,200	$ 1,200	$ 1,000
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period share issuance range	66,316
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period share issuance range	0
Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual service	3 years
Contractual term	7 years
Exercisable period month after date of grant	6 months
Shares issued to non employee director	2,093	1,905	2,199
2011 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved	2,025,000
Restricted stock vesting period	3 years
Reserved and unissued shares	863,472	1,257,996
2011 Omnibus Incentive Plan [Member] | Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual grant of shares	0
2011 Omnibus Incentive Plan [Member] | Non Employee Director [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual grant of shares	12,000
2003 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved	1,236,000
Additional grant under Plan	0
Last date till the share can be granted	Jan. 22, 2013
Reserved and unissued shares	0	0
Directors' Deferred Fee Plan [Member] | Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Units issued to non employee directors	17,969	16,561	24,191
2003 Omnibus incentive plan and 2011 Omnibus incentive plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum member of management and executive employees eligible for awards | Employee	20

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Beginning balance, options	359,375
Granted, options	117,600
Exercised, options	(118,090)
Forfeited, options	(5,360)
Ending balance, options	353,525
Exercisable options, ending balance	58,110
Beginning balance, weighted average exercise price | $ / shares	$ 22.03
Ending balance, weighted average exercise price | $ / shares	31.63
Exercisable, weighted average exercisable price | $ / shares	$ 18.53
Outstanding, weighted average remaining contractual life (years)	4 years 8 months 12 days
Exercisable, weighted average remaining contractual life (years)	2 years 1 month 6 days
Outstanding, aggregate intrinsic value | $	$ 427
Exercisable, aggregate intrinsic value | $	$ 427

Stock-Based Compensation - Su52

Stock-Based Compensation - Summary of Weighted Average Assumptions Used In Valuing Options (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk free interest rate	1.54%	1.58%	0.80%
Expected life in years	4 years 6 months	4 years 6 months	4 years 6 months
Expected volatility	40.82%	44.33%	58.50%

Stock-Based Compensation - Su53

Stock-Based Compensation - Summary of Unvested Option (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Unvested, options beginning balance	359,375
Granted, options	117,600
Vested, options	(176,200)
Forfeited, options	(5,360)
Unvested, options ending balance	295,415	359,375
Unvested , weighted average grant date fair value beginning balance	$ 9.82
Granted, weighted average grant date fair value	15.41	$ 12.12	$ 12.95
Vested, weighted average grant date fair value	5.66
Forfeited, weighted average grant date fair value	15.41
Unvested , weighted average grant date fair value ending balance	$ 13.59	$ 9.82

Stock-Based Compensation - Su54

Stock-Based Compensation - Summary of Restricted Stock Activity (Detail) - Restricted Stock [Member]	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested, options beginning balance | shares	107,939
Granted, options | shares	3,651
Vested, options | shares	(45,455)
Unvested, options ending balance | shares	66,135
Unvested , weighted average grant date fair value beginning balance | $ / shares	$ 13.90
Granted | $ / shares	41.08
Vested | $ / shares	11
Unvested , weighted average grant date fair value ending balance | $ / shares	$ 17.39

Employee Benefits - Additional

Employee Benefits - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Apr. 30, 2011	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Reinstatement of contribution matching percentage	50.00%
Contribution in operation		$ 6.4	$ 5.7	$ 2.5
Shares held by the Rabbi trust		165,971	193,607
Performance incentive accruals		$ 2.9	$ 6.5	$ 8.8
Payroll deduction for ESPP, percent of annual wages		10.00%
Shares purchased by custodians		7,327	4,751	6,711
Highly Compensated Employees [Member]
Defined Benefit Plan Disclosure [Line Items]
Payroll deduction for ESPP, percent of annual wages		20.00%
401(k)Saving Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Company match of contribution		50.00%
Employees contribution share		6.00%

Income Taxes - Summary of Defer

Income Taxes - Summary of Deferred Tax Liabilities and Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Depreciation	$ 103,471	$ 100,607
Other	3,482	(559)
Gross deferred tax liabilities	106,953	100,048
Allowance for doubtful accounts	(1,350)	(1,511)
Equity-based compensation	(3,961)	(3,440)
Employee benefits	(4,847)	(7,024)
Claims and insurance	(20,942)	(22,019)
Other	(8,436)	(7,108)
Gross deferred tax assets	(39,536)	(41,102)
Net deferred tax liability	$ 67,417	$ 58,946

Income Taxes - Summary of Incom

Income Taxes - Summary of Income Tax Provision (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current:
U.S. federal	$ 20,768	$ 18,085	$ 9,924
State	1,759	1,690	2,496
Total current income tax provision	22,527	19,775	12,420
Deferred:
U.S. federal	8,570	9,547	11,822
State	(150)	(85)	276
Total deferred income tax provision	8,420	9,462	12,098
Total income tax provision	$ 30,947	$ 29,237	$ 24,518

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax [Line Items]
Federal statutory income tax rate	35.00%
Interest related to unrecognized tax benefits	$ 0.2	$ 0.3	$ 0.1
Accrued interest and penalties related to unrecognized tax benefits	1	1.3
Unrecognized tax benefits that would affect the Company's effective tax rate if recognized	1.2	1.2
Cash (received) paid for income taxes	16.4	20.8	$ 20.6
Tax credit recognized in fourth quarter of each year	$ 1	$ 1
Maximum [Member]
Income Tax [Line Items]
Income tax year open for examination	2,015
Maximum [Member] | State and Local Jurisdiction [Member]
Income Tax [Line Items]
Income tax year open for examination	2,015
Minimum [Member]
Income Tax [Line Items]
Income tax year open for examination	2,013
Minimum [Member] | State and Local Jurisdiction [Member]
Income Tax [Line Items]
Income tax year open for examination	2,006

Income Taxes - Summary of Recon

Income Taxes - Summary of Reconciliation Between Income Taxes and Effective Income Tax Provision (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Provision at federal statutory rate, taxable amount	$ 30,087	$ 28,430	$ 23,851
State income taxes, net	2,229	2,426	2,574
Nondeductible business expenses	696	589	675
Tax credits	(1,532)	(1,434)	(2,429)
Other, net	(533)	(774)	(153)
Total income tax provision	$ 30,947	$ 29,237	$ 24,518

Income Taxes - Summary of Gross

Income Taxes - Summary of Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits at beginning of year	$ 1,165	$ 1,281
Gross increases in tax positions for current year	237	202
Lapse of statute of limitations	(244)	(318)
Gross unrecognized tax benefits at end of year	$ 1,158	$ 1,165

Summary of Quarterly Operatin61

Summary of Quarterly Operating Results (Unaudited) - Summary of Quarterly Operating Results (Unaudited) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Operating revenue	$ 287,610	$ 317,199	$ 323,480	$ 293,022	$ 309,648	$ 332,544	$ 330,399	$ 299,730	$ 1,221,311	$ 1,272,321	$ 1,139,094
Operating income	17,616	19,845	31,281	21,233	20,572	27,149	22,741	15,231	89,975	85,693	74,418
Net income	$ 11,387	$ 11,777	$ 19,247	$ 12,605	$ 13,569	$ 16,278	$ 13,568	$ 8,576	$ 55,016	$ 51,991	$ 43,627
Basic earnings per share	$ 0.46	$ 0.47	$ 0.77	$ 0.51	$ 0.55	$ 0.66	$ 0.55	$ 0.35	$ 2.21	$ 2.12	$ 1.81
Diluted earnings per share	$ 0.46	$ 0.46	$ 0.75	$ 0.49	$ 0.53	$ 0.64	$ 0.53	$ 0.34	$ 2.16	$ 2.04	$ 1.73

Acquisitions - Additional Infor

Acquisitions - Additional Information (Detail) - LinkEx, Inc [Member] - USD ($)	Feb. 02, 2015	Dec. 31, 2015	Dec. 31, 2015
Business Acquisition [Line Items]
Percentage of voting interest acquired	100.00%
Purchase price of acquisition	$ 22,200,000	$ 22,238,000
Potential earn-out subject to meeting profit targets	$ 3,000,000
Acquired intangible assets, amortization period			15 years
Identified Intangible Assets [Member]
Business Acquisition [Line Items]
Identified intangible assets, weighted-average useful life			14 years 4 months 24 days

Acquisition - Summary of Cash P

Acquisition - Summary of Cash Purchase Price Allocated Based on Independent Appraisals and Managements Estimates (Detail) - USD ($) $ in Thousands	Feb. 02, 2015	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Consideration:
Acquisition of business, net of cash received			$ (22,238)
Recognized amounts of identifiable assets acquired and liabilities assumed:
Goodwill		$ 12,025	12,025	$ 5,231	$ 5,231
LinkEx, Inc [Member]
Consideration:
Acquisition of business, net of cash received		(22,238)
Fair value of total consideration transferred	$ (22,200)	(22,238)
Acquisition related costs included in SG&A		300	300
Recognized amounts of identifiable assets acquired and liabilities assumed:
Current assets		4,337	4,337
Property and equipment		430	430
Other identifiable intangible assets		2,300	2,300
Other non-current assets		9	9
Current liabilities		(2,900)	(2,900)
Non-current liabilities		(32)	(32)
Total identifiable net assets assumed		15,444	15,444
Goodwill		6,794	6,794
Total		22,238	22,238
LinkEx, Inc [Member] | Customer Lists [Member]
Recognized amounts of identifiable assets acquired and liabilities assumed:
Other identifiable intangible assets		$ 11,300	$ 11,300

Valuation and Qualifying Acco64

Valuation and Qualifying Accounts - Summary of Valuation and Qualifying Accounts (Detail) - Allowance for Uncollectible Accounts [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance, beginning of period	$ 3,868	$ 3,737	$ 3,881
Additions - Charged to costs and expenses	1,463	1,942	2,227
Deductions	(1,880)	(1,811)	(2,371)
Balance, end of period	$ 3,451	$ 3,868	$ 3,737