Merger Narrative (Details) (Berkshire Hathaway, Inc. [Member], USD $)	1 Months Ended
	Feb. 12, 2010
Berkshire Hathaway, Inc. [Member]
Business Acquisition [Line Items]
Common stock shares owned by acquiring company prior to Merger	76,777,029
Percentage of the acquired company's total common stock shares issued and outstanding owned by the acquiring company prior to the Merger	22.50%
Common stock, par value	$ 0.01
Right to receive amount if consideration paid in cash	$ 100.00
Right to receive calculation numerator if consideration issued in stock	100.00
Percentage of total merger consideration paid in the form of cash	60.00%
Percentage of total merger consideration paid in the form of common stock	40.00%
Costs related to the merger	62,000,000
Gross amount due under contracts included in the fair value of accounts receivable acquired	862,000,000
Estimated uncollectible amount included in the fair value of accounts receivable acquired	54,000,000
Weighted average amortization life of intangible assets acquired	10 years
Weighted average amortization life of intangible liabilities acquired	16 years
Contingencies related to casualty and environmental liabilities acquired	$ 1,178,000,000