Summary Information of Reportable Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Segment Reporting Information [Line Items]
Revenues	$ 446,557	$ 420,924	$ 410,441	$ 398,126	$ 393,489	$ 362,988	$ 347,734	$ 335,177	$ 1,676,048	$ 1,439,388	$ 1,177,736
Income before income taxes									372,324	331,853	277,688
Total assets	3,177,090				2,639,023				3,177,090	2,639,023	2,182,803
Property, plant and equipment, net	293,912				267,971				293,912	267,971	246,154
United States
Segment Reporting Information [Line Items]
Revenues									1,212,111	1,083,565	912,594
Income before income taxes									316,156	277,486	232,077
Total assets	2,208,152				1,919,424				2,208,152	1,919,424	1,453,546
Property, plant and equipment, net	197,118				188,936				197,118	188,936	184,089
United States | Regulated waste management services
Segment Reporting Information [Line Items]
Revenues									1,094,928	957,398	842,479
International countries
Segment Reporting Information [Line Items]
Income before income taxes									56,168	54,367	45,611
Total assets	968,938				719,599				968,938	719,599	729,257
Property, plant and equipment, net	96,794				79,035				96,794	79,035	62,065
International countries | Regulated waste management services
Segment Reporting Information [Line Items]
Revenues									463,937	355,823	265,142
International countries | Europe
Segment Reporting Information [Line Items]
Property, plant and equipment, net	52,604				38,833				52,604	38,833	32,592
International countries | Europe | Regulated waste management services
Segment Reporting Information [Line Items]
Revenues									252,620	199,304	158,577
International countries | Other international countries
Segment Reporting Information [Line Items]
Property, plant and equipment, net	44,190				40,202				44,190	40,202	29,473
International countries | Other international countries | Regulated waste management services
Segment Reporting Information [Line Items]
Revenues									$ 211,317	$ 156,519	$ 106,565