Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Selected Quarterly Financial Data [Abstract]
Revenue	$ 81,567	$ 73,890	$ 69,443	$ 69,113	$ 73,521	$ 75,535	$ 74,286	$ 75,511	$ 294,013	$ 298,853	$ 284,924
Operating expenses	34,876	36,171	36,950	36,725	41,547	38,949	40,026	38,714	144,722	159,236	134,868
Operating (loss) income	46,691	37,719	32,493	32,388	31,974	36,586	34,260	36,797	149,291	139,617	150,056
Net income from continuing operations	$ 32,511	$ 15,297	$ 13,342	$ 10,463	$ 10,589	$ 12,451	$ 9,708	$ 13,770	$ 71,613	$ 46,518	$ 76,593
Net (loss) income per basic share attributable to CAI common stockholders	$ 1.84	$ 0.87	$ 0.76	$ 0.60	$ 0.61	$ 0.72	$ 0.55	$ 0.74	$ 1.08	$ 1.25	$ 3.76
Net (loss) income per diluted share attributable to CAI common stockholders	$ 1.81	$ 0.86	$ 0.76	$ 0.59	$ 0.60	$ 0.71	$ 0.54	$ 0.73	$ 1.06	$ 1.23	$ 3.71