Subsequent Events (Details) (USD $)	0 Months Ended		3 Months Ended				3 Months Ended
	Apr. 02, 2012	Apr. 13, 2012	Mar. 31, 2012	Mar. 31, 2011	Apr. 30, 2012	Dec. 31, 2011	Mar. 31, 2012 Bridge Loan [Member]	Mar. 31, 2012 Revolving Credit Facility [Member]	Apr. 13, 2012 Senior Notes 8.0% Due 2016 [Member]	Apr. 13, 2012 Senior Notes 8.25% Due 2019 [Member]	Jun. 30, 2011 Maximum [Member] Senior Credit Agreement [Member]	Jun. 30, 2011 Minimum [Member] Senior Credit Agreement [Member]
Subsequent Event [Line Items]
Number of towers acquired	2,275		78
Number of towers in development	42
Aggregate consideration paid, cash			$ 850,000,000
Aggregate consideration paid, Class A common stock			5,250,000
Pursuant to underwriting agreement, period in which the company cannot sell, pledge, or otherwise dispose of shares, in days			45
Bridge Loan			400,000,000
Debt instrument, maturity date							Apr. 01, 2013
Interest rate description			The bridge loan bears interest, at SBA Monarch's election, at either the Base Rate plus a margin that ranges from 2.00% to 2.50% or the Eurodollar Rate plus a margin that ranges from 3.00% to 3.50%, in each case based on SBA Monarch's ratio of Consolidated Total Debt to Consolidated Adjusted EBITDA (calculated in accordance with the Bridge Loan Credit Agreement). As of April 30, 2012, the bridge loan bears interest at the Eurodollar Rate plus 3.5% (currently 3.74%).
Debt ratio for credit agreement			7.0 to 1.0
Percentage of aggregate unpaid principal amount			50.00%
Debt instrument, principal amount											600,000,000	500,000,000
Line of credit facility, increase, additional borrowings			284,000,000
Line of credit facility, remaining borrowing capacity					116,000,000			300,000,000
Partial settlement received			4,600,000
Common stock, share, issued		6,005,000	115,974,000			109,675,000
Aggregate principal amount									131,300,000	131,300,000
Interest expense		$ 21,300,000	$ 42,248,000	$ 37,781,000