Fair Values of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Estimated Fair Value of Outstanding Debt Balances

The estimated fair value of the Company’s outstanding debt balances as of December 31, 2017 and 2016 is set forth below (in thousands):

	December 31, 2017				December 31, 2016
	Carrying		Fair		Carrying		Fair
	Value		Value		Value		Value
Borrowings under Credit Agreement:
Revolving credit facility	$	268,000	$	268,000	$	—	$	—
4.97% Series A Senior Notes		300,000		303,966		300,000		283,534
4.27% Series B Senior Notes		300,000		295,616		300,000		263,194
Total debt	$	868,000	$	867,582	$	600,000	$	546,728