Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2014 Office Source	Dec. 31, 2013	Dec. 31, 2012
Nature of Business and Significant Accounting Policies [Line Items]
Number of domestic field offices of parent company		62
Percentage of net service revenue from international operations		2.00%	2.00%	2.00%
Accounts receivable reserves as percentage of gross accounts receivable		1.00%	1.10%
Number of primary sources of revenues		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		$ 0.4	$ 1.0	$ 1.7
Economic burden for worker's compensation claim per occurrence		250,000
Defined benefit plan estimated amount of plan participants future benefits liability		275,000
Defined benefit plan estimated maximum amount of plan participants future benefits liability		500,000
Defined Benefit Plan amortization threshold percentage		10.00%
Common stock excluded from the computation of dilutive earnings per share		0	0	33,000
Dividend declared per share	$ 0.11	$ 0.41	$ 0.10	$ 1.00
Government Solutions [Member]
Nature of Business and Significant Accounting Policies [Line Items]
Time and material contracts revenue as percentage of aggregate segment revenue		69.00%
Percentage of revenue recognized on percentage of completion method		20.00%
Percentage of revenue recognized on cost plus arrangement method		11.00%
Minimum [Member]
Nature of Business and Significant Accounting Policies [Line Items]
Cost allocation period for definite-lived intangible assets		1 year
Minimum [Member] | Leasehold Improvements [Member]
Nature of Business and Significant Accounting Policies [Line Items]
Amortization period		3 years
Minimum [Member] | Computers and Software [Member]
Nature of Business and Significant Accounting Policies [Line Items]
Amortization period		1 year
Maximum [Member]
Nature of Business and Significant Accounting Policies [Line Items]
Cost allocation period for definite-lived intangible assets		15 years
Maximum [Member] | Leasehold Improvements [Member]
Nature of Business and Significant Accounting Policies [Line Items]
Amortization period		5 years
Maximum [Member] | Computers and Software [Member]
Nature of Business and Significant Accounting Policies [Line Items]
Amortization period		5 years