Fair Value Measurements (Details) (USD $)	3 Months Ended
	Dec. 31, 2014	Mar. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	$ 9,000,000
Fair Value Assumptions, Expected Volatility Rate	30.00%
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	197,443,000	259,994,000
Fair Value, Measurements, Recurring | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	48,005,000	37,886,000
Fair Value, Measurements, Recurring | Money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	149,438,000	222,108,000
Fair Value, Measurements, Recurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	48,005,000	37,886,000
Fair Value, Measurements, Recurring | Level 1 | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	48,005,000	37,886,000
Fair Value, Measurements, Recurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	149,438,000	222,108,000
Fair Value, Measurements, Recurring | Level 2 | Money market fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total cash and cash equivalents	149,438,000	222,108,000
Fair Value, Measurements, Recurring | Level 3 | Liability
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability, Noncurrent	$ 4,500,000