Condensed Financial Information of Registrant - Condensed Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 4,438	$ 4,154	$ 2,452
Investments	3,202	1,875
Receivables	2,177	1,672
Prepaid expenses and other current assets	247	175
Total current assets	10,064	7,876
Property, equipment, and capitalized software, net	396	391
Goodwill and intangible assets, net	1,252	941
Deferred income taxes	106	69
Total assets	12,209	9,532
Current liabilities:
Accounts payable, accrued liabilities and other	842	641
Total current liabilities	7,047	4,965
Long-term debt	2,173	2,127
Finance lease liabilities	219	225
Other long-term liabilities	140	119
Total liabilities	9,579	7,436
Stockholders’ equity:
Common stock, $0.001 par value; 150 million shares authorized; outstanding: 58 million shares at December 31, 2021, and 59 million at December 31, 2020	0	0
Preferred stock, $0.001 par value; 20 million shares authorized, no shares issued and outstanding	0	0
Additional paid-in capital	236	199
Accumulated other comprehensive (loss) income	(5)	37
Retained earnings	2,399	1,860
Total stockholders’ equity	2,630	2,096	$ 1,960	$ 1,647
Total liabilities and stockholders’ equity	12,209	9,532
Parent Company
Current assets:
Cash and cash equivalents	274	575
Investments	74	69
Receivables	0	2
Due from affiliates	74	114
Prepaid expenses and other current assets	142	65
Total current assets	564	825
Property, equipment, and capitalized software, net	349	339
Goodwill and intangible assets, net	699	369
Investments in subsidiaries	3,772	3,228
Deferred income taxes	(18)	5
Advances to related parties and other assets	68	83
Total assets	5,434	4,849
Current liabilities:
Accounts payable, accrued liabilities and other	378	338
Total current liabilities	378	338
Long-term debt	2,173	2,127
Finance lease liabilities	219	225
Other long-term liabilities	34	63
Total liabilities	2,804	2,753
Stockholders’ equity:
Common stock, $0.001 par value; 150 million shares authorized; outstanding: 58 million shares at December 31, 2021, and 59 million at December 31, 2020	0	0
Preferred stock, $0.001 par value; 20 million shares authorized, no shares issued and outstanding	0	0
Additional paid-in capital	236	199
Accumulated other comprehensive (loss) income	(5)	37
Retained earnings	2,399	1,860
Total stockholders’ equity	2,630	2,096
Total liabilities and stockholders’ equity	$ 5,434	$ 4,849