Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Level 3
Assets:
Total fair value	$ 0	$ 0
Fair value measurements on recurring basis | Level 1
Assets:
Total fair value	106,901	92,704
Fair value measurements on recurring basis | Level 1 | Cash and money market funds
Assets:
Total fair value	68,326	46,740
Fair value measurements on recurring basis | Level 1 | Pension plan assets
Assets:
Total fair value	38,575	45,964
Fair value measurements on recurring basis | Level 2
Assets:
Total fair value	167,538	136,047
Fair value measurements on recurring basis | Level 2 | Pension plan assets
Assets:
Total fair value	167,538	136,047
Fair value measurements on recurring basis | Total
Assets:
Total fair value	274,439	228,751
Fair value measurements on recurring basis | Total | Cash and money market funds
Assets:
Total fair value	68,326	46,740
Fair value measurements on recurring basis | Total | Pension plan assets
Assets:
Total fair value	$ 206,113	$ 182,011