Fair Value Measurements (Details) - Fair value measurements on recurring basis - Total - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Assets:
Total fair value	$ 272,706	$ 254,543
Cash and cash equivalents
Assets:
Total fair value	64,743	49,045
Defined Benefit Pension Plans
Assets:
Total fair value	207,963	205,498
Level 1
Assets:
Total fair value	138,537	120,096
Level 1 | Cash and cash equivalents
Assets:
Total fair value	64,743	49,045
Level 1 | Defined Benefit Pension Plans
Assets:
Total fair value	73,794	71,051
Level 2
Assets:
Total fair value	134,169	134,447
Level 2 | Defined Benefit Pension Plans
Assets:
Total fair value	$ 134,169	$ 134,447