Goodwill And Other Intangible Assets (Other Intangibles) (Details) (USD $)	9 Months Ended	12 Months Ended
	Dec. 31, 2012	Mar. 31, 2012
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	338,465,000	309,714,000
Accumulated Amortization	(107,996,000)	(95,510,000)
Finite-Lived Intangible Assets, Net	230,469,000	214,204,000
Intangible asset residual value	0
Estimated future amortization expense in remainder of 2013	7,000,000
Estimated future amortization expense in 2014	26,200,000
Estimated future amortization expense in 2015	24,600,000
Estimated future amortization expense in 2016	23,100,000
Estimated future amortization expense in 2017	21,200,000
Estimated future amortization expense thereafter	128,400,000
Customer relationships [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	293,374,000	270,096,000
Accumulated Amortization	(86,312,000)	(74,253,000)
Finite-Lived Intangible Assets, Net	207,062,000	195,843,000
Non-competition agreements [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	43,671,000	38,378,000
Accumulated Amortization	(20,383,000)	(20,427,000)
Finite-Lived Intangible Assets, Net	23,288,000	17,951,000
Other intangible assets [Member]
Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	1,420,000	1,240,000
Accumulated Amortization	(1,301,000)	(830,000)
Finite-Lived Intangible Assets, Net	119,000	410,000
Weighted Average [Member] | Customer relationships [Member]
Finite Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Useful Life	15 years	15 years
Weighted Average [Member] | Non-competition agreements [Member]
Finite Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Useful Life	7 years	8 years
Minimum [Member] | Customer relationships [Member]
Finite Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Useful Life	7 years
Maximum [Member] | Customer relationships [Member]
Finite Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Useful Life	17 years