Fair Value Measurements - Fair Value Assets Measured on a Non-recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable equity securities			$ 24,765
Deferred compensation plan assets	$ 765	$ 669	517
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable equity securities			24,765
Deferred compensation plan assets	0	0	0
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable equity securities			0
Deferred compensation plan assets	765	669	517
Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale marketable equity securities			0
Deferred compensation plan assets	0	0	0
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Development projects in progress	34,418		14,379
Land held for sale	19,973	8,814	4,117
Fair Value, Measurements, Nonrecurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Development projects in progress	0		0
Land held for sale	0	0	0
Fair Value, Measurements, Nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Development projects in progress	0		0
Land held for sale	0	0	0
Fair Value, Measurements, Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Development projects in progress	34,418		14,379
Land held for sale	$ 19,973	$ 8,814	$ 4,117