Quarterly Financial Data (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenues	$ 124,866	$ 120,203	$ 113,852	$ 111,506	$ 106,280	$ 104,232	$ 96,389	$ 90,370	$ 470,427	$ 397,271	$ 294,005
Operating Income (Loss)	25,149	26,086	24,655	24,348	22,912	15,275	17,013	14,877	101,805	139,782	97,023
Net Income (Loss) Attributable to Parent									(7,244)	43,467	27,681
Net Income (Loss) Available to Common Stockholders, Basic	$ (32,536)	$ (31,529)	$ (28,655)	$ (28,313)	$ 2,641	$ (14,227)	$ (26,068)	$ (5,636)	$ (121,033)	$ (43,290)	$ (35,985)
Earnings Per Share, Basic	$ (0.71)	$ (0.71)	$ (0.66)	$ (0.66)	$ 0.06	$ 0.35	$ 0.66	$ (0.14)	$ (2.73)	$ (1.08)	$ (1.13)
Weighted Average Number of Shares Outstanding, Diluted	45,934	44,703	43,703	42,680	42,046	40,300	39,383	39,098	44,265	40,032	31,926
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ (1,364)	$ (2,137)	$ (1,677)	$ (2,280)	$ 27,199	$ 8,354	$ (5,278)	$ 14,263	$ (7,458)	$ 44,538	$ 28,667
Earnings Per Share, Diluted	$ (0.71)	$ (0.71)	$ (0.66)	$ (0.66)	$ 0.06	$ 0.35	$ 0.66	$ (0.14)
Weighted Average Number of Shares Outstanding, Basic	45,934	44,703	43,703	42,680	41,320	40,300	39,383	39,098