Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2018

Fair Value [Abstract]

Carrying Values and Fair Values of Debt Instruments

The carrying values and fair values of the Company’s debt instruments where the carrying values do not approximate their fair values as of June 30, 2018 and December 31, 2017, are as follows:  

	Carrying Value at				Fair Value* at
	June 30, 2018		December 31, 2017		June 30, 2018		December 31, 2017
2018 Senior Notes	$	-	$	50,000	$	-	$	50,223
2019 Senior Notes	$	175,000	$	175,000	$	179,078	$	182,547
2021 Senior Notes	$	100,000	$	100,000	$	102,394	$	104,985
New 2021 Senior Notes	$	150,000	$	150,000	$	144,459	$	146,855
2022 Senior Notes	$	125,000	$	125,000	$	121,611	$	124,532
2023 Senior Notes	$	200,000	$	200,000	$	189,824	$	194,660
2024 Senior Notes	$	150,000	$	150,000	$	144,657	$	149,133
2025 Senior Notes	$	375,000	$	375,000	$	361,820	$	375,311
2026 Senior Notes	$	400,000	$	400,000	$	374,126	$	388,760
2027 Senior Notes	$	250,000	$	250,000	$	239,692	$	250,029

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*Senior Notes are classified as Level 2 within the fair value hierarchy.  Fair value is based on quotes of bonds with similar ratings in similar industries.