Benefit Plans (401K Plan) (Details) - USD ($) $ in Millions	12 Months Ended
Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Defined Contribution Plan Disclosure [Line Items]
Employer contributions to 401(k) plan	$ 14.0	$ 13.0	$ 12.3
Maximum [Member]
Defined Contribution Plan Disclosure [Line Items]
Defined contribution plan employer contributions, percentage of participants' wages	2.00%

The amount of the cost recognized during the period for defined contribution plans.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

Name:	us-gaap_DefinedContributionPlanCostRecognized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration