INVESTMENTS (Details 2) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Investments
Fair value of investment with greater than 5% of total investments	41,777,736,000	40,697,848,000
Aggregate investments in other than equity securities	469,700,000	364,500,000
Investment Concentration Risk | Investments.
Investments
Minimum percentage of total investments	5.00%	5.00%
Alliance Boots | Investment Concentration Risk | Investments.
Investments
Fair value of investment with greater than 5% of total investments	3,700,000,000	3,500,000,000
HCA | Investment Concentration Risk | Investments.
Investments
Fair value of investment with greater than 5% of total investments		2,100,000,000