Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2015 USD ($) Office Source subsidiary	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Nature of Business and Significant Accounting Policies [Line Items]
Number of domestic field offices of parent company | Office	62
Number of subsidiaries with international offices | subsidiary	1
Percentage of net service revenue from international operations (less than)	2.00%	2.00%	2.00%
Accounts receivable reserves as percentage of gross accounts receivable	1.10%	1.00%
Number of primary sources of revenues | Source	2
Maximum scheduled period to commence employment for search revenue recognition	30 days
Typical contingency period for occurrence of fallouts	90 days
Minimum likelihood of being realized upon settlement of uncertain tax positions	50.00%
Development-stage implementation costs of software	$ 300,000	$ 400,000	$ 1,000,000
Economic burden for worker's compensation claim per occurrence	250,000
Defined benefit plan estimated amount of plan participants future benefits liability	300,000
Defined benefit plan estimated maximum amount of plan participants future benefits liability	$ 450,000
Defined benefit plan amortization threshold percentage	10.00%
Government Solutions
Nature of Business and Significant Accounting Policies [Line Items]
Percentage of consolidated revenue	7.00%
Time and material contracts revenue as percentage of aggregate segment revenue	62.00%
Percentage of revenue recognized on percentage of completion method	16.00%
Percentage of revenue recognized on cost plus arrangement method	6.00%
Percentage of revenue recognized for product-based business	16.00%
Minimum
Nature of Business and Significant Accounting Policies [Line Items]
Cost allocation period for definite-lived intangible assets	1 year
Minimum | Leasehold Improvements
Nature of Business and Significant Accounting Policies [Line Items]
Amortization period	3 years
Minimum | Computers and Software
Nature of Business and Significant Accounting Policies [Line Items]
Amortization period	1 year
Maximum
Nature of Business and Significant Accounting Policies [Line Items]
Cost allocation period for definite-lived intangible assets	15 years
Maximum | Leasehold Improvements
Nature of Business and Significant Accounting Policies [Line Items]
Amortization period	5 years
Maximum | Computers and Software
Nature of Business and Significant Accounting Policies [Line Items]
Amortization period	5 years