Fair Value Measurement (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				3 Months Ended
	Mar. 31, 2014 transfers	Mar. 31, 2013 transfers	Mar. 31, 2014 Commercial Mortgage Backed Securities [Member] Level 2 [Member]	Dec. 31, 2013 Commercial Mortgage Backed Securities [Member] Level 2 [Member]	Mar. 31, 2014 Minimum [Member] broker
Fair Value Measurement [Line Items]
Percentage of portfolio of unadjusted fair values obtained	99.60%
Percentage of portfolio of specific unadjusted broker quotes obtained	0.40%
Number of knowledgeable outside security brokers consulted to determine fair value					1
Trading securities, fair value disclosure			$ 21.9	$ 21.9
Transfers between Levels 1, 2, and 3 of the fair value hierarchy	0	0