Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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Amount, after accumulated amortization, of debt discount (premium).

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

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Long-Term Debt and Notes Payable - Components of Long-Term Debt and Notes Payable (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Mar. 06, 2017	Dec. 31, 2016	May 28, 2013
Long-term debt and notes payable
Principal Outstanding	$ 2,744,080		$ 2,747,856
Unamortized Premium (Discount)	(13,924)		(13,734)
Unamortized Issuance Costs	(30,254)		(35,133)
Carrying Value	2,699,902		2,698,989
Fair Value	2,761,735		2,752,974
Select Excluding Concentra
Long-term debt and notes payable
Principal Outstanding	2,118,252		2,100,439
Unamortized Premium (Discount)	(11,667)		(10,961)
Unamortized Issuance Costs	(19,586)		(22,042)
Carrying Value	2,086,999		2,067,436
Fair Value	2,129,909		2,103,148
Select Excluding Concentra \| Senior notes \| 6.375% Senior Notes Due June 2021
Long-term debt and notes payable
Principal Outstanding	710,000		710,000
Unamortized Premium (Discount)	778		1,006
Unamortized Issuance Costs	(6,553)		(8,461)
Carrying Value	704,225		702,545
Fair Value	$ 727,750		$ 710,000
Interest rate of debt (as a percent)	6.375%	6.375%	6.375%	6.375%
Select Excluding Concentra \| Other
Long-term debt and notes payable
Principal Outstanding	$ 36,877		$ 22,688
Unamortized Premium (Discount)	0		0
Unamortized Issuance Costs	(533)		0
Carrying Value	36,344		22,688
Fair Value	36,344		22,688
Concentra Inc
Long-term debt and notes payable
Principal Outstanding	625,828		647,417
Unamortized Premium (Discount)	(2,257)		(2,773)
Unamortized Issuance Costs	(10,668)		(13,091)
Carrying Value	612,903		631,553
Fair Value	631,826		649,826
Concentra Inc \| Other
Long-term debt and notes payable
Principal Outstanding	6,653		5,178
Unamortized Premium (Discount)	0		0
Unamortized Issuance Costs	0		0
Carrying Value	6,653		5,178
Fair Value	6,653		5,178
Revolving facility \| Select Excluding Concentra \| Credit facility
Long-term debt and notes payable
Principal Outstanding	230,000		220,000
Unamortized Premium (Discount)	0		0
Unamortized Issuance Costs	0		0
Carrying Value	230,000		220,000
Fair Value	211,600		204,600
Term loan \| Select Excluding Concentra \| Credit facility
Long-term debt and notes payable
Principal Outstanding	1,141,375		1,147,751
Unamortized Premium (Discount)	(12,445)		(11,967)
Unamortized Issuance Costs	(12,500)		(13,581)
Carrying Value	1,116,430		1,122,203
Fair Value	1,154,215		1,165,860
Term loan \| Concentra Inc \| Credit facility
Long-term debt and notes payable
Principal Outstanding	619,175		642,239
Unamortized Premium (Discount)	(2,257)		(2,773)
Unamortized Issuance Costs	(10,668)		(13,091)
Carrying Value	606,250		626,375
Fair Value	$ 625,173		$ 644,648