Selected Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selected Quarterly Financial Information [Abstract]
Revenue	$ 183,890	$ 220,260	$ 226,693	$ 233,524	$ 236,553	$ 244,662	$ 246,821	$ 257,458	$ 864,367	$ 985,494	$ 1,122,972
Gross profit	36,217	40,533	42,095	43,275	44,657	46,827	46,647	46,770	162,120	184,901	206,557
Operating and administrative expenses	38,498	43,675	48,315	47,047	49,863	46,853	45,444	45,273	177,535	187,433	182,873
Restructuring and other related costs	0	3,478	240	49	3,604	566	0	47	3,767	4,217	3,645
Impairment					0	21,537	0	0	0	21,537	14,653
Loss on disposition of business interests	0	11,301	0	0	0	0	0	310	11,301	310	0
Operating loss	(2,281)	(17,921)	(6,460)	(3,821)	(8,810)	(22,129)	1,203	1,140	(30,483)	(28,596)	5,386
Loss before income taxes	(2,556)	(18,033)	(6,912)	(3,970)	(9,348)	(21,446)	1,106	1,153	(31,471)	(28,535)	5,158
Net income (loss)	(1,454)	(17,818)	(7,484)	(4,817)	(17,114)	(20,202)	(157)	387	(31,573)	(37,086)	3,017
Net income attributable to CDI	$ (1,454)	$ (17,818)	$ (7,484)	$ (4,817)	$ (17,114)	$ (20,202)	$ (157)	$ 470	$ (31,573)	$ (37,003)	$ 3,082
Earnings (loss) per common share:
Basic (in dollars per share)	$ (0.08)	$ (0.96)	$ (0.39)	$ (0.24)	$ (0.87)	$ (1.03)	$ (0.01)	$ 0.02	$ (1.66)	$ (1.88)	$ 0.16
Diluted (in dollars per share)	$ (0.08)	$ (0.96)	$ (0.39)	$ (0.24)	$ (0.87)	$ (1.03)	$ (0.01)	$ 0.02	$ (1.66)	$ (1.88)	$ 0.16
Change in valuation allowance - foreign loss carryforwards		$ 8,864							$ 11,047	$ 14,963	$ 70
Impairment									0	21,034
Impairment charge										500
Pretax gain on sale of assets										800
Proceeds from sale of assets									(45)	(1,236)	(75)
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount					$ 11,800				11,000	15,000
Specialty Talent and Technology [Member]
Selected Quarterly Financial Information [Abstract]
Operating loss									800
Enterprise Talent [Member]
Selected Quarterly Financial Information [Abstract]
Revenue									495,955	595,963	728,686
Gross profit									56,362	71,928	88,738
Restructuring and other related costs									433	1,084	1,001
Operating loss									(7,504)	(1,448)	24,594
Earnings (loss) per common share:
Impairment									0	10,654
Engineering Solutions [Member]
Selected Quarterly Financial Information [Abstract]
Revenue									243,298	294,941	303,237
Gross profit									59,210	73,391	79,184
Restructuring and other related costs									2,690	2,153	2,092
Operating loss									(10,238)	(12,840)	$ (12,309)
Project related disputes									(1,000)
Earnings (loss) per common share:
Impairment									$ 0	10,380
Impairment charge										$ 504