Debt (Tables)

9 Months Ended

Sep. 30, 2017

Debt Disclosure [Abstract]

Schedule of Debt

Our total debt consisted of the following at September 30, 2017 and December 31, 2016:

	September 30, 2017			December 31, 2016
Senior unsecured notes
2.50% Senior Notes due March 2017	$	—		$	299,992
5.75% Senior Notes due March 2018	249,911			249,771
7.50% Senior Notes due March 2019	201,695			201,695
4.90% Senior Notes due August 2020	167,612			167,576
4.625% Senior Notes due March 2021	208,561			208,538
3.95% Senior Notes due March 2022	125,510			125,488
7.75% Senior Notes due January 2024	981,738			980,117
7.70% Senior Notes due April 2025	448,983			448,909
6.20% Senior Notes due August 2040	399,899			399,898
6.05% Senior Notes due March 2041	397,790			397,758
5.25% Senior Notes due March 2042	498,393			498,369
8.70% Senior Notes due April 2045	394,647			394,613
Total debt	4,074,739			4,372,724
Less: Unamortized debt issuance costs	(29,760		)	(32,613		)
Less: Current maturities of long-term debt (1)	(249,652		)	(299,882		)
Long-term debt, net of debt issuance costs	$	3,795,327		$	4,040,229

⁽¹⁾  Presented net of current portion of unamortized debt issuance costs of $0.3 million and $0.1 million at September 30, 2017 and December 31, 2016, respectively.

Estimated Fair Value of Our Long-Term Debt, not Including Effect of Unamortized Debt Issuance Costs

The following table presents the estimated fair value of our total debt, not including the effect of unamortized debt issuance costs, as of September 30, 2017 and December 31, 2016, respectively:

	September 30, 2017				December 31, 2016
	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value
Senior unsecured notes:
2.50% Senior Notes due March 2017	$	—	$	—	$	299,992	$	299,128
5.75% Senior Notes due March 2018	249,911		252,638		249,771		249,808
7.50% Senior Notes due March 2019	201,695		208,347		201,695		209,524
4.90% Senior Notes due August 2020	167,612		164,664		167,576		167,329
4.625% Senior Notes due March 2021	208,561		194,303		208,538		196,416
3.95% Senior Notes due March 2022	125,510		104,816		125,488		112,791
7.75% Senior Notes due January 2024	981,738		890,160		980,117		945,317
7.70% Senior Notes due April 2025	448,983		386,802		448,909		423,267
6.20% Senior Notes due August 2040	399,899		278,956		399,898		280,221
6.05% Senior Notes due March 2041	397,790		274,376		397,758		273,854
5.25% Senior Notes due March 2042	498,393		329,460		498,369		325,814
8.70% Senior Notes due April 2045	394,647		325,600		394,613		328,608
Total debt	$	4,074,739	$	3,410,122	$	4,372,724	$	3,812,077