Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis

We record transfers between levels of the fair value hierarchy, if necessary, at the end of the reporting period. There were no transfers between levels for the periods presented.

December 31, 2018	Quoted Prices in Active Markets for Identical Assets or Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Margin Cash Collateral Offset		Total Net Fair Value
	(in thousands)
Restricted cash equivalents	$	6,669	$	—	$	—	$	—	$	6,669
Rabbi trust investments	22,270		—		—		—		22,270
Total	$	28,939	$	—	$	—	$	—	$	28,939
December 31, 2017
Restricted cash equivalents	2,648		$	—	$	—	$	—	$	2,648
Rabbi trust investments	28,135		—		—		—		28,135
Total	$	30,783	$	—	$	—	$	—	$	30,783

Schedule of Estimated Fair Value of Financial Instruments

The estimated fair value of financial instruments is summarized as follows (in thousands):

	December 31, 2018				December 31, 2017
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Liabilities:
Long-term debt	$	2,102,345	$	2,117,912	$	1,793,416	$	1,901,915