Short-term Investments (Estimated Fair Value Of Short-Term Investments By Contractual Maturity) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014
Short-Term Investments And Fair Value Measurement [Abstract]
Due within one year	$ 204,050
Due after one year and through 5 years	306,743
Due after 5 years and through 10 years	0
Due after 10 years	0
Total short-term investments	$ 510,793