Quarterly Financial Information (Unaudited) Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ 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
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 309,687	$ 302,534	$ 297,584	$ 279,541	$ 273,803	$ 261,531	$ 259,875	$ 253,573	$ 1,189,346	$ 1,048,782	$ 1,002,286
(Loss) income from operations	3,975	5,547	(167)	(2,592)	6,021	14,847	13,375	17,668	6,763	51,911	59,391
Net income (loss)	$ (2,375)	$ (21,097)	$ 4,524	$ (534)	$ (6,943)	$ 9,588	$ 8,559	$ 24,524	$ (19,482)	$ 35,728	$ (33,933)
Basic earnings per share
Basic (loss) earnings per share	$ (0.01)	$ (0.09)	$ 0.02	$ 0	$ (0.03)	$ 0.04	$ 0.04	$ 0.11	$ (0.08)	$ 0.15	$ (0.15)
Diluted earnings per share
Diluted (loss) earnings (loss) per share	$ (0.01)	$ (0.09)	$ 0.02	$ 0	$ (0.03)	$ 0.04	$ 0.03	$ 0.10	$ (0.08)	$ 0.14	$ (0.15)