Debt (Schedule of Cash and Non-Cash Interest Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Cash Interest	$ 390,036	$ 376,217	$ 323,749
Non-cash Interest	3,193	2,640	2,879
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Cash Interest	7,085	7,411	8,046
2014 Senior Notes [Member]
Debt Instrument [Line Items]
Cash Interest	36,563	36,563	36,563
Non-cash Interest	800	761	724
2016 Senior Notes [Member]
Debt Instrument [Line Items]
Cash Interest	53,625	53,625	53,625
Non-cash Interest	1,055	1,003	954
2017 Senior Notes [Member]
Debt Instrument [Line Items]
Cash Interest	30,000	30,000	6,500
2012 Secured Tower Revenue Securities [Member]
Debt Instrument [Line Items]
Cash Interest			5,330
2013 Secured Tower Revenue Securities [Member]
Debt Instrument [Line Items]
Cash Interest	21,584	25,654	43,217
2014 Tower Securities [Member]
Debt Instrument [Line Items]
Cash Interest	43,055	51,138	51,138
2015-1C Tower Securities [Member]
Debt Instrument [Line Items]
Cash Interest	15,939	15,939	15,939
2016-1C Tower Securities [Member]
Debt Instrument [Line Items]
Cash Interest	20,361	20,361	20,361
2017-1C Tower Securities [Member]
Debt Instrument [Line Items]
Cash Interest	24,354	24,354	17,182
2018-1C Tower Securities [Member]
Debt Instrument [Line Items]
Cash Interest	22,281	18,072
2019-1C Tower Securities [Member]
Debt Instrument [Line Items]
Cash Interest	10,029
2014 Term Loan [Member]
Debt Instrument [Line Items]
Cash Interest		15,550	49,414
Non-cash Interest		146	525
2015 Term Loan [Member]
Debt Instrument [Line Items]
Cash Interest		5,237	16,641
Non-cash Interest		187	676
2018 Term Loan [Member]
Debt Instrument [Line Items]
Cash Interest	105,021	72,648
Non-cash Interest	1,338	543
Capitalized Interest And Other [Member]
Debt Instrument [Line Items]
Cash Interest	$ 139	$ (335)	$ (207)