Derivative Instruments (Current Period Cash Flow Hedges in AOCI (loss) before Taxes) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
AOCI Cash Flow Hedges [Roll Forward]
Balance beginning	$ (4,578)	$ 403
Gains (losses) deferred in other comprehensive income (loss) on the effective portion of cash flow hedges	776	1,863
Amounts reclassified to investment income	(218)	(305)
Balance ending	$ (4,020)	$ 1,961