Debt and Credit Agreements (Details)			1 Months Ended	3 Months Ended	12 Months Ended
	Apr. 01, 2016	Mar. 27, 2015 USD ($) bank	Mar. 31, 2012 USD ($) bank	Mar. 31, 2015 USD ($)	Mar. 31, 2016	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Debt Instrument [Line Items]
Financing costs expensed				$ 600,000
Senior Notes | 2.7% Notes due October 15, 2015
Debt Instrument [Line Items]
Stated interest rate (in percent)				2.70%		2.70%
Line of Credit
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 500,000,000	$ 525,000,000
Number of lenders | bank		11	14
Contingent increase to maximum borrowing capacity		$ 550,000,000
Calculated total net debt to consolidated EBITDA ratio						2.7
Calculated proportion of subsidiary consolidated indebtedness to consolidated tangible assets (percent)						0.80%
Calculated total consolidated EBITDA to consolidated interest charges						6.3
Outstanding borrowings						$ 100,000,000	$ 98,500,000
Line of Credit | Scenario, Forecast [Member]
Debt Instrument [Line Items]
Net debt to consolidated EBITDA ratio	3.5				3.75