Employee Benefit Plans - Additional Information (Detail) $ / shares in Units, shares in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2013 USD ($) Participant	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) Participant $ / shares shares
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Accrued matching contribution		$ 1,400,000	$ 1,300,000
Kforce common stock held by both plans | shares		218	229
Percentage of discount on shares purchased under employee stock purchase plan		5.00%
Employee stock purchase plan (in shares) | shares		26	35	41
Average purchase price (in dollars per share) | $ / shares		$ 22.61	$ 19.76	$ 14.88
Deferred Compensation Liability, Classified, Noncurrent		$ 24,238,000	$ 22,425,000
Gains (losses) attributable to the investments in bond mutual funds		0	0	$ (15,000)
Number of participants terminated | Participant	2
Rabbi Trust
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Assets held in Rabbi Trust		25,489,000	25,715,000
Non-Qualified Deferred Compensation Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred compensation plan, amount included in accounts payable and other accrued liabilities		2,300,000	3,700,000
Deferred Compensation Liability, Classified, Noncurrent		24,200,000	22,400,000
Compensation expenses (income)		$ 401,000	$ (187,000)	$ 566,000
Foreign Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan arrangement minimum age		60 years
Completed at least credited service period		5 years
Defined benefit plan assumptions used calculating benefit obligation benefits payable per service year		one-half month’s salary for each year of credited service
Discount rate used to determine the actuarial present value of the projected benefit obligation and pension expense	5.00%	5.20%	4.70%	5.00%
Estimated rate of future annual compensation increases	3.00%	3.00%	3.00%	3.00%
Net periodic benefit cost		$ 280,000	$ 124,000	$ 92,000
Defined benefit plan obligation		1,200,000	$ 1,600,000
Employer contributions to benefit plans		$ 0
Foreign Pension Plan | Minimum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Age group of employees for company turnover rate		20 years
Foreign Pension Plan | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Age group of employees for company turnover rate		64 years
Supplemental Executive Retirement Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan arrangement minimum age		55 years
Completed at least credited service period		10 years
Discount rate used to determine the actuarial present value of the projected benefit obligation and pension expense		4.00%	3.75%
Net periodic benefit cost		$ 1,706,000	$ 1,458,000	2,610,000
Defined benefit plan obligation	$ 7,852,000	$ 11,337,000	10,197,000	7,852,000
Normal retirement age		65 years
Early retirement age		55 years
Vesting percentage under plan for attaining age 55 and 10 years		100.00%
Vesting percentage under plan prior to attaining age 55 and 10 years		0.00%
Define benefit plan employees minimum requisition period under specific conditions		5 years
Benefits payable targeted percentage		45.00%
Period in which the executive officer earned the highest salary and bonus		3 years
Employment period For computation of benefit		10 years
Eligible age under condition one for reduced benefits under the plan		62 years
Eligible service under condition one for reduced benefits under plan		10 years
Eligible age under condition two for reduced benefits under plan		55 years
Eligible service under condition two for reduced benefits under plan		25 years
Lump sum payment period		10 years
Payments made under the SERP		$ 0	0
Accumulated benefit obligation		11,000,000	9,500,000
Employer contributions to benefit plans		$ 0
Supplemental Executive Retirement Health Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit cost			977,000	510,000
Defined benefit plan obligation	$ 2,674,000		0	2,674,000
Payments made under the SERP			3,900,000
Settlement gain (loss)			$ (725,000)	$ 359,000
Number of participants terminated | Participant				2
Curtailment				$ 785,000
Curtailment gain				$ 359,000