Derivative Instruments (Details 3) (Interest Rate Swap [Member], USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Derivatives In Cash Flow Hedging Relationships [Line Items]
Gains Losses Deferred In Accumulated Other Comprehensive Income Loss On Derivatives	$ 2,613,000	$ (628,000)
Investment Related Gains Losses [Member]
Derivatives In Cash Flow Hedging Relationships [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	0	0
Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing, Net	(41,000)	0
Investment Income [Member]
Derivatives In Cash Flow Hedging Relationships [Line Items]
Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion	$ 1,382,000	$ 200,000