Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Fair value of financial instruments

The estimated fair values of our financial instruments, all of which are categorized in Level 1 of the fair value hierarchy, as of March 31, 2018 and December 31, 2017 have been calculated based upon available market information, and were as follows:

	March 31, 2018				December 31, 2017
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Senior notes	$	7,008	$	7,108	$	7,008	$	7,340