Schedule I Condensed Balance Sheets (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	$ 7,495	$ 7,276	$ 8,406	$ 9,429
Total current assets	23,556	20,380
Long-term notes receivable from subsidiaries		2,600
Other assets	2,972	2,439
Total assets	86,382	81,882	80,885
Accounts payable and accrued liabilities	9,247	7,458
Commercial paper and current maturities of long-term debt	1,399	1,969
Total current liabilities	30,623	27,881
Long-term debt, less current maturities	16,007	14,891
Total liabilities	52,540	48,558
Commitments and contingencies (Note 4)
Preferred stock, $0.001 par value - 10 shares authorized; no shares issued or outstanding	0	0
Common stock, $0.01 par value - 3,000 shares authorized; 954 and 988 issued and outstanding	10	10
Retained earnings	33,836	33,047
Accumulated other comprehensive loss	(1,392)	(908)
Total UnitedHealth Group shareholders’ equity	32,454	32,149	31,178	28,292
Total liabilities and shareholders’ equity	86,382	81,882
Parent [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Cash and cash equivalents	559	822	1,025	1,506
Short-term notes receivable from subsidiaries	27	11
Deferred income taxes and other current assets	271	214
Total current assets	857	1,047
Equity in net assets of subsidiaries	44,643	44,301
Long-term notes receivable from subsidiaries	4,635	4,215
Other assets	278	144
Total assets	50,413	49,707
Accounts payable and accrued liabilities	332	335
Note payable to subsidiary	215	215
Commercial paper and current maturities of long-term debt	1,365	1,935
Total current liabilities	1,912	2,485
Long-term debt, less current maturities	15,891	14,804
Deferred income taxes and other liabilities	156	269
Total liabilities	17,959	17,558
Preferred stock, $0.001 par value - 10 shares authorized; no shares issued or outstanding	0	0
Common stock, $0.01 par value - 3,000 shares authorized; 954 and 988 issued and outstanding	10	10
Retained earnings	33,836	33,047
Accumulated other comprehensive loss	(1,392)	(908)
Total UnitedHealth Group shareholders’ equity	32,454	32,149
Total liabilities and shareholders’ equity	$ 50,413	$ 49,707