Fair Value Measurements and Derivative Instruments (Available-For-Sale Securities) (Details) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 357,339,000	$ 325,368,000
Gross unrealized gains	6,836,000	3,504,000
Gross unrealized losses	(2,133,000)	(6,580,000)
Estimated fair value	362,042,000us-gaap_AvailableForSaleSecurities	322,292,000us-gaap_AvailableForSaleSecurities
Investment securities at a loss position for more than 12 months, aggregate unrealized holding losses	1,000,000	1,000,000
Investment securities at a loss position for more than 12 months, estimated fair value	42,000,000	19,000,000
Investment securities at a loss position for less than 12 months, unrealized holding losses	1,000,000	6,000,000
Investment securities at a loss position for less than 12 months, estimated fair value	88,000,000	166,000,000
U.S. and foreign governments, agencies and municipalities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	135,839,000	121,803,000
Gross unrealized gains	2,905,000	999,000
Gross unrealized losses	(764,000)	(3,372,000)
Estimated fair value	137,980,000	119,430,000
Corporate
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	66,170,000	37,901,000
Gross unrealized gains	1,569,000	935,000
Gross unrealized losses	(291,000)	(572,000)
Estimated fair value	67,448,000	38,264,000
Mortgage-backed / asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	155,330,000	165,664,000
Gross unrealized gains	2,362,000	1,570,000
Gross unrealized losses	(1,078,000)	(2,636,000)
Estimated fair value	$ 156,614,000	$ 164,598,000

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months.

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