Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Fair Value Assets Transfers between Level 1 and Level 2) (Details) (Available-for-sale Securities [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value Assets, Level 1 to level 2 Transfers During Period, Amount	$ 0	$ 0
Fair Value Assets, Level 2 to Level 1 Transfers During Period, Amount	0	14,012
Corporate securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value Assets, Level 1 to level 2 Transfers During Period, Amount	0	0
Fair Value Assets, Level 2 to Level 1 Transfers During Period, Amount	$ 0	$ 14,012