Summary of Significant Accounting Policies (Per Share Information) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended																12 Months Ended
	Dec. 31, 2018	[1]	Sep. 30, 2018	[1]	Jun. 30, 2018	[1]	Mar. 31, 2018	[1]	Dec. 31, 2017	[1]	Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Income (Loss) from Continuing Operations																	$ 671	$ 445	$ 357
Dividends, Preferred Stock																	(113)	(58)	(33)
Net income (loss) attributable to CCIC common stockholders																	$ 558	$ 387	$ 324
Weighted-average common shares outstanding:
Basic weighted-average number of common stock outstanding																	413	382	340
Diluted weighted-average number of common shares outstanding																	415	383	341
Net income (loss) attributable to CCIC common stockholders, after deduction of dividends on preferred stock, per common share:
Basic (in dollars per share)	$ 0.45		$ 0.33		$ 0.37		$ 0.21		$ 0.17		$ 0.22		$ 0.31		$ 0.33		$ 1.35	$ 1.01	$ 0.95
Diluted (in dollars per share)	$ 0.44		$ 0.33		$ 0.36		$ 0.21		$ 0.17		$ 0.21		$ 0.31		$ 0.33		1.34	1.01	0.95
Common Stock, Dividends, Per Share, Declared																	$ 4.28	$ 3.90	$ 3.61
Stock Options and Restricted Stock Awards [Member]
Weighted-average common shares outstanding:
Effect of assumed dilution from potential common shares relating to stock options and restricted stock awards																	2	1	1

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