Debt (Tables)

3 Months Ended

Mar. 31, 2017

Debt Disclosure [Abstract]

Schedule of Senior Notes

Our senior notes are summarized as follows ($000’s omitted):

	March 31, 2017			December 31, 2016
7.625% unsecured senior notes due October 2017 (a)	123,000			123,000
4.250% unsecured senior notes due March 2021 (b)	700,000			700,000
5.500% unsecured senior notes due March 2026 (b)	700,000			700,000
5.000% unsecured senior notes due January 2027 (b)	600,000			600,000
7.875% unsecured senior notes due June 2032 (b)	300,000			300,000
6.375% unsecured senior notes due May 2033 (b)	400,000			400,000
6.000% unsecured senior notes due February 2035 (b)	300,000			300,000
Net premiums, discounts, and issuance costs (c)	(12,996		)	(12,984		)
Total senior notes	$	3,110,004		$	3,110,016
Estimated fair value	$	3,206,575		$	3,112,297

(a) Not redeemable prior to maturity; guaranteed on a senior basis by certain wholly-owned subsidiaries.

(b) Redeemable prior to maturity; guaranteed on a senior basis by certain wholly-owned subsidiaries.

(c) The carrying value of senior notes reflects the impact of premiums, discounts, and issuance costs that are amortized to interest cost over the respective terms of the senior notes.