Fair Value of Financial Instruments (Fair Value Measurements for Level 3 Instruments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	$ 0	$ 25,276	$ 8,118	$ 26,166
Total realized and unrealized gains (losses):
Included in net income	0	0	0	0
Included in other comprehensive income	0	(1,802)	897	(2,060)
Purchases, sales, issuances and settlements, net	0	30	0	(602)
Transfers into (out of) Level 3	0	0	(9,015)	0
Balance at end of period	0	23,504	0	23,504
Amount of total gains (losses) for the period included in net income attributable to the change in unrealized gains (losses) relating to assets still held at the end of period	0	0	0	0
Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	2,217	3,090	1,647	4,512
Total realized and unrealized gains (losses):
Included in net income	(166)	(1,375)	422	(2,240)
Included in comprehensive income	0	0	0	0
Purchases, sales, issuances and settlements, net	(48)	0	(66)	(557)
Transfers into (out of) Level 3	0	0	0	0
Balance at end of period	2,003	1,715	2,003	1,715
Amount of total gains (losses) for the period included in net income attributable to the change in unrealized gains (losses) relating to assets still held at end of period	(68)	(1,375)	583	(1,642)
Debt Securities, Available for Sale [Member]
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	0	17,157	0	18,602
Total realized and unrealized gains (losses):
Included in net income	0	0	0	0
Included in other comprehensive income	0	(1,802)	0	(2,615)
Purchases, sales, issuances and settlements, net	0	30	0	(602)
Transfers into (out of) Level 3	0	0	0	0
Balance at end of period	0	15,385	0	15,385
Amount of total gains (losses) for the period included in net income attributable to the change in unrealized gains (losses) relating to assets still held at the end of period	0	0	0	0
Equity Securities, Available for Sale [Member]
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Beginning balance	0	8,119	8,118	7,564
Total realized and unrealized gains (losses):
Included in net income	0	0	0	0
Included in other comprehensive income	0	0	897	555
Purchases, sales, issuances and settlements, net	0	0	0	0
Transfers into (out of) Level 3	0	0	(9,015)	0
Balance at end of period	0	8,119	0	8,119
Amount of total gains (losses) for the period included in net income attributable to the change in unrealized gains (losses) relating to assets still held at the end of period	$ 0	$ 0	$ 0	$ 0

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