Reconciliation of Reportable Segment Assets to Corresponding Consolidated Amounts (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Sep. 30, 2012
Segment Reporting, Asset Reconciling Item [Line Items]
Investments in cash, cash equivalents, restricted cash and marketable securities	$ 142,757	$ 200,994
Long-term deferred tax assets	101,135	104,626
Investments in joint ventures	30,437	31,428
Other unallocated corporate net assets	29,146	22,463
Total assets	724,829	741,960
Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 421,354	$ 382,449