Earnings per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Numerator [Abstract]
Net income attributable to CAI common stockholders used in the calculation of basic and diluted earnings per share	$ 16,528	$ 13,622	$ 46,054	$ 37,298
Denominator [Abstract]
Weighted average shares used in the calculation of basic earnings per share (in shares)	19,295	19,295	19,295	19,295
Effect of dilutive securities (in shares)	469	286	435	432
Weighted average shares used in the calculation of diluted earnings per share (in shares)	19,764	19,581	19,730	19,727
Net income per share attributable to CAI common stockholders [Abstract]
Basic (in dollars per share)	$ 0.86	$ 0.71	$ 2.39	$ 1.93
Diluted (in dollars per share)	$ 0.84	$ 0.70	$ 2.33	$ 1.89