Investments (Impaired Mortgage Loans) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012		Dec. 31, 2012
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	$ 33,298				$ 33,298				$ 40,566
Recorded Investment	32,624				32,624				39,956
Related Allowance	4,691				4,691				6,980
Carrying Value	27,933				27,933				32,976
Average Investment	35,121	[1]	46,101	[1]	37,841	[1]	52,490	[1]
Interest Income	615		570		1,334		1,485
Impaired mortgage loans with valuation allowance recorded
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	21,536				21,536				27,527
Recorded Investment	21,467				21,467				27,460
Related Allowance	4,691				4,691				6,980
Carrying Value	16,776				16,776				20,480
Average Investment	21,490	[1]	35,047	[1]	24,337	[1]	36,178	[1]
Interest Income	266		461		801		1,180
Impaired mortgage loans with no valuation allowance recorded
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance	11,762				11,762				13,039
Recorded Investment	11,157				11,157				12,496
Related Allowance	0				0				0
Carrying Value	11,157				11,157				12,496
Average Investment	13,631	[1]	11,054	[1]	13,504	[1]	16,312	[1]
Interest Income	$ 349		$ 109		$ 533		$ 305

[1] Average recorded investment represents the average loan balances as of the beginning of period and all subsequent quarterly end of period balances.