Acquisitions - Unaudited Pro Forma (Details) - USD ($) $ / shares in Units, $ in Thousands	2 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Business Acquisition [Line Items]
Revenue		$ 1,066,421	$ 900,510	$ 2,015,946	$ 1,744,666
Net income (loss) from continuing operations		$ 45,805	$ 39,302	$ 87,867	$ 1,975
Basic EPS (in dollars per share)		$ 0.59	$ 0.64	$ 1.17	$ 0.20
Diluted EPS (in dollars per share)		$ 0.58	$ 0.64	$ 1.16	$ 0.20
Verizon [Member]
Business Acquisition [Line Items]
Revenue	$ 86,700	$ 86,700		$ 86,700
Verizon [Member] | Pro Forma [Member]
Business Acquisition [Line Items]
Revenue		1,101,848	$ 1,010,833	2,157,653	$ 1,965,312
Net income (loss) from continuing operations		$ 74,831	$ 30,673	$ 124,160	$ (58,993)
Basic EPS (in dollars per share)		$ 0.96	$ 0.40	$ 1.60	$ (0.79)
Diluted EPS (in dollars per share)		$ 0.95	$ 0.40	$ 1.58	$ (0.79)