Condensed Consolidated Statement Of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Statement of Other Comprehensive Income [Abstract]
Net income	$ 85,519	$ 59,466	$ 158,350	$ 124,934
Other comprehensive gains (losses), net of tax:
Unrealized holding gain (loss)	18	(951)	(48)	(1,495)
Reclassification adjustment for loss included in net income	436	599	874	935
Total other comprehensive gain (loss)	454	(352)	826	(560)
Comprehensive income	$ 85,973	$ 59,114	$ 159,176	$ 124,374

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the economic entity, including both controlling (parent) and noncontrolling interests. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, including any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References+ Details

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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+ Details

- Definition

Net of tax amount of other comprehensive income (loss) attributable to the parent entity.

+ References

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- Definition

Net of tax amount of the income statement impact of the reclassification adjustment of accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges realized in net income. Also includes reclassification adjustments of an entity's share of an equity investee's deferred hedging gain (loss) realized in net income.

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- Definition

Net of tax amount, before reclassification adjustments, of the change in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Also includes an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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