Financial Instruments	6 Months Ended
Jun. 30, 2015
Financial Instruments [Abstract]
Financial Instruments	7. Financial Instruments The fair value of financial instruments is determined by reference to observable market data and other valuation techniques as appropriate. The only category of financial instruments where the difference between fair value and recorded book value is notable is long-term debt. The estimated fair value of total long-term debt, excluding capitalized lease obligations, was $19,001 million at June 30, 2015, and $11,660 million at December 31, 2014, as compared to recorded book values of $18,857 million at June 30, 2015, and $11,278 million at December 31, 2014. The increase in the estimated fair value and book value of long-term debt reflects the Corporation’s issuance of $8.0 billion of long-term debt in the first quarter of 2015. The $8.0 billion of long-term debt is comprised of $500 million of floating-rate notes due in 2018, $500 million of floating-rate notes due in 2022, $1,600 million of 1.305% notes due in 2018, $1,500 million of 1.912% notes due in 2020, $1,150 million of 2.397% notes due in 2022, $1,750 million of 2.709% notes due in 2025, and $1,000 million of 3.567% notes due in 2045. The fair value of long-term debt by hierarchy level at June 30, 2015, is: Level 1 $18,577 million; Level 2 $362 million; and Level 3 $62 million. Level 1 represents quoted prices in active markets. Level 2 includes debt whose fair value is based upon a publicly available index. Level 3 involves using internal data augmented by relevant market indicators if available.

7. Financial Instruments

The fair value of financial instruments is determined by reference to observable market data and other valuation techniques as appropriate. The only category of financial instruments where the difference between fair value and recorded book value is notable is long-term debt. The estimated fair value of total long-term debt, excluding capitalized lease obligations, was $19,001 million at June 30, 2015, and $11,660 million at December 31, 2014, as compared to recorded book values of $18,857 million at June 30, 2015, and $11,278 million at December 31, 2014. The increase in the estimated fair value and book value of long-term debt reflects the Corporation’s issuance of $8.0 billion of long-term debt in the first quarter of 2015. The $8.0 billion of long-term debt is comprised of $500 million of floating-rate notes due in 2018, $500 million of floating-rate notes due in 2022, $1,600 million of 1.305% notes due in 2018, $1,500 million of 1.912% notes due in 2020, $1,150 million of 2.397% notes due in 2022, $1,750 million of 2.709% notes due in 2025, and $1,000 million of 3.567% notes due in 2045.

The fair value of long-term debt by hierarchy level at June 30, 2015, is: Level 1 $18,577 million; Level 2 $362 million; and Level 3 $62 million. Level 1 represents quoted prices in active markets. Level 2 includes debt whose fair value is based upon a publicly available index. Level 3 involves using internal data augmented by relevant market indicators if available.