Selected Quarterly Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Summary of Selected Quarterly Data

	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

	2017
($ in thousands, except per share data)	Fourth Quarter		Third Quarter		Second Quarter			First Quarter
Revenues	$	128,024	$	123,675	$	94,132		$	79,776
Operating Income (Loss)	28,015		16,789		3,184			10,047
Net Income (Loss)	5,643		20,523		28			13,745
Net Income (Loss) Attributable to Common Stockholders	3,414		16,708		(2,389		)	10,943
Earnings (loss) per share—Basic	$	0.48	$	2.32	$	(0.34	)	$	1.67
Earnings (loss) per share—Diluted	$	0.46	$	2.21	$	(0.34	)	$	1.62