Segment Information Reconciliation of Reportable Segment Assets to Corresponding Consolidated Amounts (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2012
Segment Reporting, Asset Reconciling Item [Line Items]
Investments in cash, cash equivalents, restricted cash and marketable securities	$ 145,574	$ 200,994
Deferred tax assets	118,011	120,157
Investments in joint ventures	28,425	31,428
Other unallocated corporate net assets	14,677	6,932
Total assets	721,762	741,960
Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 415,075	$ 382,449