Acquisitions - Unaudited Pro Forma (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		5 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Revenues	$ 1,152,261	$ 924,676		$ 3,168,207	$ 2,669,342
Net income (loss) from continuing operations	$ 79,900	$ 48,769		$ 167,767	$ 50,744
Basic EPS (in dollars per share)	$ 1.02	$ 0.73		$ 2.20	$ 0.94
Diluted EPS (in dollars per share)	$ 1.02	$ 0.72		$ 2.18	$ 0.92
Verizon [Member]
Business Acquisition [Line Items]
Revenues	$ 137,000		$ 223,700	$ 223,700
Verizon [Member] | Pro Forma [Member]
Business Acquisition [Line Items]
Revenues	1,152,261	$ 1,034,999		3,309,381	$ 3,000,311
Net income (loss) from continuing operations	$ 80,135	$ 35,069		$ 194,504	$ (37,410)
Basic EPS (in dollars per share)	$ 1.03	$ 0.45		$ 2.50	$ (0.49)
Diluted EPS (in dollars per share)	$ 1.02	$ 0.45		$ 2.48	$ (0.49)