Selected Quarterly Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Summary of Selected Quarterly Data

	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

	2018
($ in thousands, except per share data)	Fourth Quarter		Third Quarter		Second Quarter		First Quarter
Revenues	$	138,065	$	152,210	$	132,932	$	129,028
Operating Income (Loss)	29,228		33,946		27,308		22,617
Net Income (Loss)	1,093		27,931		23,229		23,827
Net Income (Loss) Attributable to Common Stockholders	77		24,913		20,986		21,216
Earnings (loss) per share—Basic	$	0.01	$	3.47	$	2.91	$	2.95
Earnings (loss) per share—Diluted	$	0.01	$	3.19	$	2.75	$	2.77