Acquisitions - Schedule of Acquisition Capital Expenditures (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Business Combinations [Abstract]
Towers and related intangible assets	$ 80,326	$ 21,736	$ 311,190	$ 951,331
Ground lease land purchases	11,320	9,154	35,864	25,907
Earnouts		708	1,311	5,751
Total acquisition capital expenditures	$ 91,646	$ 31,598	$ 348,365	$ 982,989