Income Taxes (Effective Tax Rate) (Details) - USD ($) $ in Thousands		3 Months Ended								12 Months Ended
		Dec. 31, 2016	[2]	Sep. 30, 2016	[2]	Jun. 30, 2016	[2]	Mar. 31, 2016	[2]	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes (Effective Tax Rate)
Benefit (provision) for income taxes at statutory rate										$ (130,849)	$ (165,840)	$ (117,274)
Tax effect of foreign income (losses)										1,215	(527)	(4,296)
Tax adjustment related to REIT operations										121,092	186,649	(132,951)
Tax adjustment related to the small cell REIT conversion	[1]									0	(33,759)	0
Expenses for which no federal tax benefit was recognized										(43)	(414)	(463)
Valuation allowances										(21)	3,000	9,000
State tax (provision) benefit, net of federal										(1,085)	1,210	(3,136)
Foreign tax										(7,421)	(6,723)	(7,232)
Other										231	343	1,694
Total benefit (provision) for income taxes		$ (4,084)		$ (5,041)		$ (3,884)		$ (3,872)		$ (16,881)	$ 51,457	$ 11,244

[1] During the fourth quarter of 2015, the Company de-recognized the net deferred tax liabilities related to the Company's small cells previously included in one or more TRSs in conjunction with the inclusion of small cells in the REIT in January 2016.

[2] Inclusive of the tax adjustment of $33.8 million in conjunction with the inclusion of small cells in the REIT in January 2016 . See also notes 11 and 19.