Fair Value Measurements (Summary of Quantitative Information About Level 3 Fair Value Measurements) (Details)	12 Months Ended	3 Months Ended
	Dec. 31, 2014	Mar. 31, 2014
Auction Rate Securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Discounted Cash Flow, Valuation Techniques	Discounted cash flow
Private Equity Funds [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Market Comparable Companies, Valuation Techniques	Market comparable companies
Minimum [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Estimated Market Recovery Period, Years		3 years
Minimum [Member] | Auction Rate Securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Estimated Market Rate, Percent	2.10%
Minimum [Member] | Private Equity Funds [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Earnings Before Interest, Tax, Depreciation And Amortization Multiple	4.0
Maximum [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Estimated Market Recovery Period, Years		5 years
Maximum [Member] | Auction Rate Securities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Estimated Market Rate, Percent	5.30%
Maximum [Member] | Private Equity Funds [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Earnings Before Interest, Tax, Depreciation And Amortization Multiple	5.5