Debt

6 Months Ended

Jun. 30, 2012

Debt

Debt

11.  Debt

Senior Notes: Summarized below are the carrying values of our senior notes at June 30, 2012 and December 31, 2011:

	June 30, 2012		December 31, 2011
2.450% senior notes due 2015	$	523,660	$	527,191
3.950% senior notes due 2020		498,909		498,854
5.700% senior notes due 2040		249,543		249,540
Total long-term debt	$	1,272,112	$	1,275,585

At June 30, 2012, the fair value of our outstanding Senior Notes was $1.318 billion and represented a Level 2 measurement within the fair value measurement hierarchy.

Commercial Paper:  The carrying value of Commercial Paper as of June 30, 2012 and December 31, 2011 was $390.4 million and $401.4 million, respectively, and approximated its fair value.  The effective interest rate on the outstanding Commercial Paper balance at June 30, 2012 was 0.5%.

Senior Unsecured Credit Facility:  We maintain a senior unsecured revolving credit facility, or the Credit Facility, that provides revolving credit in the aggregate amount of $1.0 billion.  Amounts may be borrowed in U.S. dollars for working capital, capital expenditures and other corporate purposes. The Credit Facility serves as backup liquidity for our Commercial Paper borrowings.  As of June 30, 2012 and December 31, 2011, there was no outstanding borrowing against the Credit Facility.

The Credit Facility contains affirmative and negative covenants including certain customary financial covenants.  We were in compliance with all financial debt covenants as of June 30, 2012.

Credit Facility:  In November 2011, we entered into an uncommitted facility, or the Facility, not exceeding an aggregate $125.0 million.  As of December 31, 2011, $125.0 million was outstanding under the Facility and accounted for as short-term borrowings.  The outstanding balance was repaid in January 2012 and there was no outstanding borrowing under the Facility as of June 30, 2012.