Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Financial Instruments Measured on Recurring Basis

The carrying amounts and estimated fair values of our senior notes were as follows:

		March 31, 2018				December 31, 2017
Financial Instrument	Fair Value Input Level	Carrying Value		Fair Value		Carrying Value		Fair Value
		(In thousands)
Liabilities:
6% Senior notes	Level 2	495,452		511,740		495,308		525,120
		$	495,452	$	511,740	$	495,308	$	525,120