Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Estimated Fair Values of Financial Instruments

The estimated fair values of financial instruments are as follows (in thousands):

	March 31, 2018				December 31, 2017
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Financial liabilities:
Notes payable	$	172,246	$	172,246	$	94,515	$	94,515
5 3/4% Senior Notes due 2019	—		—		149,362		151,500
7% Senior Notes due 2022	346,924		359,625		346,740		362,250
6% Senior Notes due 2023	343,274		349,125		—		—
5 7/8% Senior Notes due 2025	439,903		436,500		439,567		459,000