Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Jun. 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	95,674	92,705
Fair value measurements on recurring basis | Level 1 | Cash and money market funds
Assets:
Total fair value	43,566	46,740
Fair value measurements on recurring basis | Level 1 | U.S. pension plan assets
Assets:
Total fair value	35,868	30,239
Fair value measurements on recurring basis | Level 1 | U.S. pension plan assets | U.S. common stock mutual fund
Assets:
Total fair value	35,868	30,239
Fair value measurements on recurring basis | Level 1 | U.K. pension plan assets
Assets:
Total fair value	16,240	15,726
Fair value measurements on recurring basis | Level 1 | U.K. pension plan assets | Bond Funds
Assets:
Total fair value	1,705	7,297
Fair value measurements on recurring basis | Level 1 | U.K. pension plan assets | Equity Funds
Assets:
Total fair value	6,772	6,322
Fair value measurements on recurring basis | Level 1 | U.K. pension plan assets | Other funds
Assets:
Total fair value	7,763	2,107
Fair value measurements on recurring basis | Level 1 | Pension plan assets
Assets:
Total fair value	52,108	45,965
Fair value measurements on recurring basis | Level 2
Assets:
Total fair value	144,372	136,046
Fair value measurements on recurring basis | Level 2 | U.S. pension plan assets
Assets:
Total fair value	144,372	136,046
Fair value measurements on recurring basis | Level 2 | U.S. pension plan assets | Bond Funds
Assets:
Total fair value	73,954	62,554
Fair value measurements on recurring basis | Level 2 | U.S. pension plan assets | Common /collective funds, Short-term money market
Assets:
Total fair value	2,739	6,762
Fair value measurements on recurring basis | Level 2 | U.S. pension plan assets | Common /collective funds, U.S. common stock
Assets:
Total fair value	60,137	59,677
Fair value measurements on recurring basis | Level 2 | U.S. pension plan assets | Common /collective funds, International equity
Assets:
Total fair value	7,542	7,053
Fair value measurements on recurring basis | Level 2 | Pension plan assets
Assets:
Total fair value	144,372	136,046
Fair value measurements on recurring basis | Total
Assets:
Total fair value	240,046	228,751
Fair value measurements on recurring basis | Total | Cash and money market funds
Assets:
Total fair value	43,566	46,740
Fair value measurements on recurring basis | Total | U.S. pension plan assets
Assets:
Total fair value	180,240	166,285
Fair value measurements on recurring basis | Total | U.S. pension plan assets | U.S. common stock mutual fund
Assets:
Total fair value	35,868	30,239
Fair value measurements on recurring basis | Total | U.S. pension plan assets | Bond Funds
Assets:
Total fair value	73,954	62,554
Fair value measurements on recurring basis | Total | U.S. pension plan assets | Common /collective funds, Short-term money market
Assets:
Total fair value	2,739	6,762
Fair value measurements on recurring basis | Total | U.S. pension plan assets | Common /collective funds, U.S. common stock
Assets:
Total fair value	60,137	59,677
Fair value measurements on recurring basis | Total | U.S. pension plan assets | Common /collective funds, International equity
Assets:
Total fair value	7,542	7,053
Fair value measurements on recurring basis | Total | U.K. pension plan assets
Assets:
Total fair value	16,240	15,726
Fair value measurements on recurring basis | Total | U.K. pension plan assets | Bond Funds
Assets:
Total fair value	1,705	7,297
Fair value measurements on recurring basis | Total | U.K. pension plan assets | Equity Funds
Assets:
Total fair value	6,772	6,322
Fair value measurements on recurring basis | Total | U.K. pension plan assets | Other funds
Assets:
Total fair value	7,763	2,107
Fair value measurements on recurring basis | Total | Pension plan assets
Assets:
Total fair value	$ 196,480	$ 182,011