Derivative Financial Instruments Outstanding Interest Rate Swap Agreements (Details) - USD ($) $ in Thousands		6 Months Ended
	Sep. 30, 2016	Jun. 30, 2016
Interest Rate Swap 1 [Member]
Derivative [Line Items]
Effective Date		Sep. 30, 2015
Expiration Date		Sep. 30, 2016
Interest Rate Swap 2 [Member]
Derivative [Line Items]
Effective Date		Sep. 30, 2016
Expiration Date		Sep. 30, 2026
Interest Rate Swap 3 [Member]
Derivative [Line Items]
Effective Date		Sep. 30, 2016
Expiration Date		Sep. 30, 2026
Interest Rate Swap 4 [Member]
Derivative [Line Items]
Effective Date		Sep. 30, 2016
Expiration Date		Sep. 30, 2026
Notional Period 1 [Member] | Interest Rate Swap 1 [Member]
Derivative [Line Items]
Notional Amount		$ 350,000
Pay Fixed Rate		0.93%
Notional Period 1 [Member] | Interest Rate Swap 2 [Member]
Derivative [Line Items]
Notional Amount		$ 100,000
Pay Fixed Rate		2.79%
Notional Period 1 [Member] | Interest Rate Swap 3 [Member]
Derivative [Line Items]
Notional Amount		$ 100,000
Pay Fixed Rate		2.79%
Notional Period 1 [Member] | Interest Rate Swap 4 [Member]
Derivative [Line Items]
Notional Amount		$ 100,000
Pay Fixed Rate		2.80%
Scenario, Forecast [Member]
Derivative [Line Items]
Expected settlement date of 10-year forward starting interest rate swaps	Sep. 30, 2016
Scenario, Forecast [Member] | Fixed rate debt [Member]
Derivative [Line Items]
Probable future debt	$ 300,000
Scenario, Forecast [Member] | Variable rate debt [Member]
Derivative [Line Items]
Probable future debt	$ 300,000