Goodwill and Other Intangible Assets (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2012

Dec. 31, 2011

Goodwill and Other Intangible Assets [Abstract]

Summary of intangible assets

	Estimated Life (Years)	March 31, 2012				December 31, 2011
		Gross  Carrying Amount		Accumulated Amortization		Gross  Carrying Amount		Accumulated Amortization
Amortizable Intangible Assets:
Customer lists and contracts	7 – 10	$	469,149	$	453,475	$	468,371	$	451,524
Non-competition agreements	3 – 15		63,604		62,068		63,592		61,849
Site locations	15		1,386,752		948,580		1,383,076		925,291
Other	5 – 15		13,608		13,111		13,608		13,103
		$	1,933,113	$	1,477,234	$	1,928,647	$	1,451,767
Unamortizable Intangible Assets:
Goodwill		$	1,680,841	$	253,635	$	1,680,483	$	253,635

	Estimated	2011				2010
	Life (Years)	Gross  Carrying Amount		Accumulated Amortization		Gross  Carrying Amount		Accumulated Amortization
Amortizable Intangible Assets:
Customer lists and contracts	7 — 10	$	468,371	$	451,524	$	466,412	$	441,641
Non-competition agreements	3 — 15		63,592		61,849		63,493		60,955
Site locations	15		1,383,076		925,291		1,375,298		833,418
Other	5 — 15		13,608		13,103		13,608		13,074
		$	1,928,647	$	1,451,767	$	1,918,811	$	1,349,088
Unamortizable Intangible Assets: Goodwill		$	1,680,483	$	253,635	$	1,679,770	$	253,635

Summary of changes in the gross carrying amount of goodwill

Balance as of December 31, 2010	$	1,679,770
Goodwill acquired during the year		775
Purchase price adjustments and other		(62	)
Impairment losses		—
Balance as of December 31, 2011	$	1,680,483

Summary of the estimated amortization expense

Year ended December 31, 2012	$	99,917
Year ended December 31, 2013		97,165
Year ended December 31, 2014		83,200
Year ended December 31, 2015		46,770
Year ended December 31, 2016		36,267
Thereafter		113,561
Total	$	476,880