SEGMENT INFORMATION (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Segment information
Revenues	$ 864,536	$ 840,197	$ 838,309	$ 844,572	$ 829,447	$ 819,785	$ 769,982	$ 732,588	$ 3,387,614	$ 3,151,802	$ 2,543,894
Long-Lived Assets	4,676,103				4,351,571				4,676,103	4,351,571	3,677,070
Receivables	621,420				620,489				621,420	620,489
Operating revenues | Customer concentration | Customer one
Segment information
Concentration percentage									10.80%	5.70%	2.60%
Operating revenues | Customer concentration | Customer two
Segment information
Concentration percentage									10.50%	9.60%	11.50%
Receivables | Customer concentration
Segment information
Receivables	101,600				109,900				101,600	109,900
United States
Segment information
Revenues									3,011,760	2,864,570	2,276,118
Long-Lived Assets	4,345,950				4,039,770				4,345,950	4,039,770	3,423,185
Colombia
Segment information
Revenues									100,052	82,247	74,504
Long-Lived Assets	81,315				84,389				81,315	84,389	67,369
Argentina
Segment information
Revenues									73,208	54,317	44,205
Long-Lived Assets	83,149				81,886				83,149	81,886	78,221
Ecuador
Segment information
Revenues									67,890	56,448	42,598
Long-Lived Assets	63,894				38,265				63,894	38,265	28,439
Other foreign
Segment information
Revenues									134,704	94,220	106,469
Long-Lived Assets	$ 101,795				$ 107,261				$ 101,795	$ 107,261	$ 79,856