Summary of Significant Accounting Policies (Per Share Information) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended																6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2019	[1]	Sep. 30, 2019		Jun. 30, 2019		Mar. 31, 2019		Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net income (loss)			$ 242	[1]	$ 216	[1]	$ 193	[1]	$ 201	[1]	$ 151	[1]	$ 170	[1]	$ 100	[1]	$ 409	$ 270	$ 652	$ 421	$ 860	$ 622	$ 366
Net income (loss)							193								100		409	270	652	421	860	622	366
Dividends, Preferred Stock			(28)		(28)		(28)		(28)		(28)		(28)		(28)		(57)	(57)	(85)	(85)	(113)	(113)	(58)
Net income (loss) attributable to CCIC common stockholders			$ 214		$ 188		$ 165		$ 173		$ 123		$ 142		$ 72		$ 352	$ 213	$ 567	$ 336	$ 747	$ 509	$ 308
Weighted-average common shares outstanding:
Basic weighted-average number of common stock outstanding			416		416		415		415		415		415		409		415	412	416	413	416	413	382
Diluted weighted-average number of common shares outstanding			418		418		417		417		416		416		410		417	413	418	414	418	415	383
Net income (loss) attributable to CCIC common stockholders, after deduction of dividends on preferred stock, per common share:
Basic (in dollars per share)	$ 0.43		$ 0.51	[1]	$ 0.45	[1]	$ 0.40	[1]	$ 0.42	[1]	$ 0.30	[1]	$ 0.34	[1]	$ 0.18	[1]	$ 0.85	$ 0.52	$ 1.36	$ 0.81	$ 1.80	$ 1.23	$ 0.80
Diluted (in dollars per share)	$ 0.43		$ 0.51	[1]	$ 0.45	[1]	$ 0.40	[1]	$ 0.42	[1]	$ 0.30	[1]	$ 0.34	[1]	$ 0.18	[1]	$ 0.84	$ 0.52	$ 1.36	$ 0.81	1.79	1.23	0.80
Common Stock, Dividends, Per Share, Declared																					$ 4.58	$ 4.28	$ 3.90
Restricted Stock Units (RSUs) [Member]
Weighted-average common shares outstanding:
Effect of assumed dilution from potential common shares relating to stock options and restricted stock awards																					2	2	1

[1] The sum of quarterly information may not agree to year-to-date information due to rounding.