Subsequent Events (Details) $ / shares in Units, $ in Thousands		3 Months Ended				12 Months Ended
		Dec. 31, 2016 USD ($) $ / shares	Sep. 30, 2016 $ / shares	Jun. 30, 2016 $ / shares	Mar. 31, 2016 $ / shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Subsequent Event [Line Items]
Credit Facility Amendment, Date						Feb. 13, 2017
Credit Facility Amendment, Additional Principal						$ 500,000
Debt and Capital Lease Obligations		$ 12,171,142				12,171,142	$ 12,149,959
Common Stock, Dividends, Per Share, Cash Paid | $ / shares		$ 0.95	$ 0.885	$ 0.885	$ 0.885
FiberNet Acquisition [Member]
Subsequent Event [Line Items]
Business Combination, Consideration Transferred						$ 1,500,000
Business Acquisition, Date of Acquisition Agreement						Jan. 17, 2017
Dividend Declared [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Dividends Payable, Date Declared						Feb. 17, 2017
Dividends Payable, Date to be Paid						Mar. 31, 2017
Dividends Payable, Date of Record						Mar. 17, 2017
Paid subsequent to year end [Member]
Subsequent Event [Line Items]
Common Stock, Dividends, Per Share, Cash Paid | $ / shares		$ 0.950
Issuance of debt obligation [Member] | 4.000% Senior Unsecured Notes [Member]
Subsequent Event [Line Items]
Debt Instrument, Issuance Date						Feb. 02, 2017
Debt Instrument, Face Amount		$ 500,000				$ 500,000
Debt Instrument, Interest Rate, Stated Percentage	[1],[2]	4.00%				4.00%
Debt Instrument Maturity Date Range	[1],[2]					Mar. 01, 2027
Issuance of debt obligation [Member] | 2016 Term Loan A [Member]
Subsequent Event [Line Items]
Debt Instrument Maturity Date Range	[1],[2]					Jan. 21, 2022
FiberNet Acquisition [Member]
Subsequent Event [Line Items]
Fiber Miles Acquired						11,500
FiberNet Acquisition [Member] | Top Metro Markets [Domain]
Subsequent Event [Line Items]
Fiber Miles Acquired						6,000

[1] Represents the weighted-average stated interest rate.

[2] The 2016 Revolver and senior unsecured term loan A ("2016 Term Loan A") bear interest at a rate per annum equal to LIBOR plus a credit spread ranging from 1.125% to 2.000%, based on the Company's senior unsecured debt rating. The Company pays a commitment fee of approximately 0.200% per annum on the undrawn available amount under the 2016 Revolver.