Debt (Tables)

12 Months Ended

Dec. 31, 2014

Debt Disclosure [Abstract]

Schedule of Debt

Long-term debt consists of the following at December 31, 2014 and 2013:

	December 31,		December 31,
	2014		2013
Senior unsecured notes:
7.375% Senior Notes due 2014	$	—	$	249,964
3.45% Senior Notes due 2015		350,000		350,000
3.05% Senior Notes due 2016		299,982		299,967
2.50% Senior Notes due 2017		299,920		299,886
7.50% Senior Notes due 2019		201,695		201,695
4.90% Senior Notes due 2020		499,151		499,022
4.625% Senior Notes due 2021		399,627		399,576
3.95% Senior Notes due 2022		399,264		399,178
6.20% Senior Notes due 2040		399,895		399,893
6.05% Senior Notes due 2041		397,681		397,646
5.25% Senior Notes due 2042		498,310		498,283
Total senior unsecured notes		3,745,525		3,995,110
Credit facilities & commercial paper program		1,123,495		1,561,141
Total long-term debt	$	4,869,020	$	5,556,251

Repayments of Total Debt

Aggregate principal repayments of total debt for the next five years and thereafter are as follows:

2015(1)(2)	2016		2017		2018		2019		Thereafter		Total
$1,473,495	$	299,982	$	299,920	$	—	$	201,695	$	2,593,928	$	4,869,020

(1) In August 2015, our $350 million 3.45% Senior Notes mature. We anticipate using availability on our Credit Facilities or commercial paper issuances to repay the outstanding balance; therefore, we have shown the entire balance as long-term on our Consolidated Balance Sheet at December 31, 2014.

(2) Amounts outstanding under our credit facilities and commercial paper program mature during 2015. As amounts issued under the commercial paper program are supported by the unused committed capacity under our Credit Facilities, they are classified as long-term on our Consolidated Balance Sheet at December 31, 2014.

Estimated Fair Value of Our Long-Term Debt

The following table presents the estimated fair value of our long-term debt as of December 31, 2014 and 2013:

	December 31, 2014				December 31, 2013
	Carrying		Estimated		Carrying		Estimated
	Value		Fair Value		Value		Fair Value
Senior unsecured notes:
7.375% Senior Notes due 2014	$	—	$	—	$	249,964	$	253,634
3.45% Senior Notes due 2015		350,000		354,992		350,000		363,019
3.05% Senior Notes due 2016		299,982		302,515		299,967		309,878
2.50% Senior Notes due 2017		299,920		287,014		299,886		302,891
7.50% Senior Notes due 2019		201,695		212,068		201,695		232,839
4.90% Senior Notes due 2020		499,151		471,095		499,022		528,597
4.625% Senior Notes due 2021		399,627		363,837		399,576		413,868
3.95% Senior Notes due 2022		399,264		346,425		399,178		390,520
6.20% Senior Notes due 2040		399,895		350,351		399,893		421,720
6.05% Senior Notes due 2041		397,681		343,653		397,646		417,312
5.25% Senior Notes due 2042		498,310		385,181		498,283		476,873
Total senior unsecured notes		3,745,525		3,417,131		3,995,110		4,111,151
Credit facilities and commercial paper program		1,123,495		1,123,495		1,561,141		1,561,141
Total long-term debt	$	4,869,020	$	4,540,626	$	5,556,251	$	5,672,292