Employee Benefit Plans - Additional Information (Detail) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended			0 Months Ended
	Dec. 31, 2013 Participant	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jan. 03, 2012 tranche	Apr. 30, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative Long Term Incentive Payment						$ 9,800,000
Accrued matching contribution		1,300,000	1,000,000
Kforce common stock held by both plans	317	229	317
Percentage of discount on shares purchased under employee stock purchase plan		5.00%
Employee stock purchase plan, shares		35	41	51
Average purchase price		$ 19.76	$ 14.88	$ 12.55
Gains (losses) attributable to the investments in bond mutual funds		0	(15,000)	519,000
Number of participants terminated	2
Alternative Long-Term Incentive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Number of tranches					3
Alternative long term incentive expense		0	0	9,800,000
Tranche One [Member] | Alternative Long-Term Incentive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative measurement periods					12 months
Tranche Two [Member] | Alternative Long-Term Incentive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative measurement periods					24 months
Tranche Three [Member] | Alternative Long-Term Incentive [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Alternative measurement periods					36 months
Rabbi Trust [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Assets held in Rabbi Trust	24,910,000	25,715,000	24,910,000
Non-Qualified Deferred Compensation Plan [Member]
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	3,100,000	3,700,000	3,100,000
Deferred compensation plan, amount included in other long term liability	22,200,000	22,400,000	22,200,000
Compensation expenses		187,000	566,000	635,000
Foreign Pension Plan [Member]
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%	4.70%	5.00%	6.00%
Estimated rate of future annual compensation increases		3.00%
Net periodic benefit cost		124,000	92,000	128,000
Defined benefit plan, benefit obligation	1,400,000	1,600,000	1,400,000
Foreign Pension Plan [Member] | Minimum [Member]
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 [Member] | Maximum [Member]
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 [Member]
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	3.75%	3.75%	3.75%
Net periodic benefit cost		1,458,000	2,610,000	2,811,000
Defined benefit plan, benefit obligation	7,852,000	10,197,000	7,852,000	19,658,000
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
Eligible service under condition one for reduced benefits under plan		10 years
Eligible age under condition one for reduced benefits under the plan		62 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
Number of participants terminated	2
Curtailment	2,100,000	0	2,138,000
Defined benefit plan accumulated benefit obligation non-current	7,852,000	10,197,000	7,852,000
Contributions made to the SERP		0
Lump-sum payment to the participant in SERHP	10,700,000
Supplemental Executive Retirement Health Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Net periodic benefit cost		977,000	510,000	1,341,000
Defined benefit plan, benefit obligation	2,674,000	0	2,674,000	3,574,000
Number of participants terminated	2
Curtailment	785,000
Defined benefit plan accumulated benefit obligation non-current	2,627,000	0	2,627,000
Lump-sum payment to the participant in SERHP		3,900,000
Settlement gain (loss)		(725,000)	359,000	0
Curtailment gain	359,000
Defined benefit plan accumulated benefit obligation current	47,000		$ 47,000