Summary Of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Summary Of Significant Accounting Policies [Abstract]

Schedule Of Asset Classes And Related Estimated Useful Lives

Towers and related components	3 - 15  years
Furniture, equipment and vehicles	2 - 7 years
Buildings and improvements	10 - 30  years

Allowance For Doubtful Accounts

	For the year ended December 31,
	2017		2016		2015
		(in thousands)
Beginning balance	$	24,518	$	1,681	$	889
Provision for doubtful accounts		2,909		22,516		896
Write-offs, net of recoveries		(647)		(614)		(72)
Currency translation adjustment		(299)		935		(32)
Ending balance	$	26,481	$	24,518	$	1,681

Summary Of Asset Retirement Obligation Liability

	For the year ended December 31,
	2017		2016		2015
	(in thousands)
Beginning balance	$	6,442	$	6,309	$	5,856
Additions		818		1,091		781
Currency translation adjustment		(10)		121		(57)
Accretion expense		665		318		373
Removal		(280)		(290)		(50)
Revision in estimates		(421)		(1,107)		(594)
Ending balance	$	7,214	$	6,442	$	6,309