Cash, Cash Equivalents, And Marketable Securities Cash, Cash Equivalents, And Marketable Securities narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Cash and Cash Equivalents [Abstract]
Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value	$ 1,685,882	$ 1,233,076
Available-for-sale Debt Securities Gross Unrealized Gain	$ 1,000