Investments (Mortgage Loans and Real Estate) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended			12 Months Ended
	Sep. 30, 2013		Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012	Dec. 31, 2012
Mortgage Loans on Real Estate [Line Items]
Mortgage loan, amount	$ 117,741			$ 117,741			$ 142,820
Allowance for possible losses, amount	(650)			(650)			(650)
Totals, amount	117,091	[1]		117,091	[1]		142,170	[1]
Mortgage loans, percentage	100.00%			100.00%			100.00%
Allowance for possible losses, percentage	(0.60%)			(0.60%)			(0.50%)
Totals, percentage	99.40%	[1]		99.40%	[1]		99.50%	[1]
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period				650		4,571	4,571
Provision				0			650
Releases				0			(4,571)
Balance, end of period	650			650			650
Net gain on sale of real estate investment	55		2,644	55		2,485
Other Long-term Investments [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Net gain on sale of real estate investment			2,700
Less than 50% [Member]
Mortgage Loans on Real Estate [Line Items]
Mortgage loan, amount	47,155			47,155			58,754
Mortgage loans, percentage	40.00%			40.00%			41.10%
50% to 60% [Member]
Mortgage Loans on Real Estate [Line Items]
Mortgage loan, amount	16,841			16,841			27,832
Mortgage loans, percentage	14.30%			14.30%			19.50%
60% to 70% [Member]
Mortgage Loans on Real Estate [Line Items]
Mortgage loan, amount	21,063			21,063			23,518
Mortgage loans, percentage	17.90%			17.90%			16.50%
70% to 80% [Member]
Mortgage Loans on Real Estate [Line Items]
Mortgage loan, amount	9,766			9,766			9,431
Mortgage loans, percentage	8.30%			8.30%			6.60%
80% to 90% [Member]
Mortgage Loans on Real Estate [Line Items]
Mortgage loan, amount	0			0			0
Mortgage loans, percentage	0.00%			0.00%			0.00%
Greater than 90% [Member]
Mortgage Loans on Real Estate [Line Items]
Mortgage loan, amount	$ 22,916			$ 22,916			$ 23,285
Mortgage loans, percentage	19.50%			19.50%			16.30%

[1] Loan-to-Value Ratio using the most recent appraised value.