Selected Quarterly Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2020

Quarterly Financial Information Disclosure [Abstract]

Summary of Selected Quarterly Data

	2020
(in thousands, except per share data)	Fourth Quarter		Third Quarter		Second Quarter		First Quarter
Revenues	$	171,646	$	154,790	$	132,894	$	144,566
Operating Income (Loss)	50,931		41,009		26,622		24,602
Net Income (Loss)	61,814		40,934		16,209		1,006
Net Income (Loss) Attributable to Common Stockholders	43,315		29,648		11,279		(4,285)
Earnings (loss) per share—Basic	$	5.67	$	3.86	$	1.46	$	(0.58)
Earnings (loss) per share—Diluted	$	5.40	$	3.71	$	1.43	$	(0.58)

	2019
(in thousands, except per share data)	Fourth Quarter		Third Quarter		Second Quarter		First Quarter
Revenues	$	146,084	$	145,955	$	140,489	$	130,718
Operating Income (Loss)	37,796		35,787		30,128		20,999
Net Income (Loss)	29,782		25,359		27,899		22,468
Net Income (Loss) Attributable to Common Stockholders	20,808		22,000		24,842		19,662
Earnings (loss) per share—Basic	$	3.02	$	3.17	$	3.55	$	2.80
Earnings (loss) per share—Diluted	$	2.83	$	2.95	$	3.26	$	2.61