Fair Value Measurements (Details) - Estimate of Fair Value Measurement - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 30, 2014
Fair Value, Inputs, Level 3
Assets:
Total fair value	$ 0	$ 0
Fair Value, Measurements, Recurring
Assets:
Total fair value	254,543	262,833
Fair Value, Measurements, Recurring | Cash and Cash Equivalents
Assets:
Total fair value	49,045	45,871
Fair Value, Measurements, Recurring | Pension Plan, Defined Benefit
Assets:
Total fair value	205,498	216,962
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1
Assets:
Total fair value	120,096	87,839
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | Cash and Cash Equivalents
Assets:
Total fair value	49,045	45,871
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 1 | Pension Plan, Defined Benefit
Assets:
Total fair value	71,051	41,968
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2
Assets:
Total fair value	134,447	174,994
Fair Value, Measurements, Recurring | Fair Value, Inputs, Level 2 | Pension Plan, Defined Benefit
Assets:
Total fair value	$ 134,447	$ 174,994