Basic and Diluted Earnings Per Share (EPS) Data Numerator and Denominator Calculation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Earnings Per Share, Basic and Diluted [Abstract]
Net income attributable to CDI	$ 2,427	$ 4,528	$ 3,438	$ 2,491	$ 4,992	$ 5,349	$ 4,952	$ 3,823	$ 12,884	$ 19,116	$ 14,833
Basic weighted-average shares (in shares)									19,442,000	19,344,000	19,144,000
Dilutive effect o stock-based awards (in shares)									297,000	401,000	212,000
Diluted weighted-average shares (in shares)									19,739,000	19,745,000	19,356,000
Basic (in dollars per share)	$ 0.13	$ 0.23	$ 0.18	$ 0.13	$ 0.26	$ 0.27	$ 0.26	$ 0.20	$ 0.66	$ 0.99	$ 0.77
Diluted (in dollars per share)	$ 0.12	$ 0.23	$ 0.17	$ 0.13	$ 0.25	$ 0.27	$ 0.25	$ 0.20	$ 0.65	$ 0.97	$ 0.77
Shares excluded from computation of EPS (in shares)									459,000	425,000	729,000