Fair Value Measurements (Details 3) (USD $)	3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 30, 2013 Investment securities:	Sep. 30, 2012 Investment securities:	Sep. 30, 2013 Investment securities:	Sep. 30, 2012 Investment securities:	Sep. 30, 2013 Bonds:	Sep. 30, 2012 Bonds:	Sep. 30, 2013 Bonds:	Sep. 30, 2012 Bonds:	Sep. 30, 2013 Corporate debt	Sep. 30, 2012 Corporate debt	Sep. 30, 2013 Corporate debt	Sep. 30, 2012 Corporate debt	Sep. 30, 2013 RMBS	Sep. 30, 2012 RMBS	Sep. 30, 2013 RMBS	Sep. 30, 2012 RMBS	Sep. 30, 2012 CMBS	Sep. 30, 2013 CMBS	Sep. 30, 2012 CMBS	Jun. 30, 2013 CMBS	Sep. 30, 2013 CDO/ABS	Sep. 30, 2012 CDO/ABS	Sep. 30, 2013 CDO/ABS	Sep. 30, 2012 CDO/ABS	Sep. 30, 2013 Other long-term investments	Sep. 30, 2012 Other long-term investments	Sep. 30, 2013 Other long-term investments	Sep. 30, 2012 Other long-term investments	Sep. 30, 2012 Common stocks
Changes in Level 3 assets and liabilities measured at fair value on a recurring basis
Balance at beginning of period	$ 23,275,000	$ 22,292,000	$ 28,416,000	$ 25,704,000						$ 21,797,000	$ 19,585,000	$ 27,036,000	$ 21,574,000	$ 13,114,000		$ 13,417,000	$ 2,800,000	$ 218,000	$ 2,025,000	$ 74,000	$ 1,914,000	$ 7,864,000	$ 153,000	$ 7,944,000	$ 2,000	$ 8,463,000	$ 9,696,000	$ 13,392,000	$ 8,916,000	$ 1,478,000	$ 2,707,000	$ 1,380,000	$ 4,127,000	$ 3,000
Net gains (losses) included in: Other revenues	(9,000)	(155,000)	463,000							(9,000)	(155,000)	461,000	5,000	(58,000)	(19,000)	(167,000)	(16,000)		(207,000)	(35,000)	(171,000)	(29,000)	(8,000)	(40,000)		49,000	100,000	671,000	232,000			2,000		(5,000)
Net gains (losses) included in: Other comprehensive income (loss)	(222,000)	(112,000)	(174,000)	922,000						(119,000)	84,000	(178,000)	1,600,000	18,000	8,000	305,000	192,000	(133,000)	(362,000)	46,000	(170,000)	59,000	6,000	342,000		(4,000)	379,000	(535,000)	1,236,000	(103,000)	(196,000)	4,000	(680,000)	2,000
Purchases, sales, issues, settlements	1,941,000	(781,000)	(3,720,000)	(5,382,000)		1,941,000		(3,720,000)		1,941,000	(781,000)	(3,709,000)	(4,446,000)	2,016,000		1,535,000	(2,987,000)		(62,000)		(179,000)	(456,000)	(149,000)	(808,000)		(75,000)	(263,000)	(5,095,000)	(472,000)			(11,000)	(936,000)
Transfers into Level 3		19,302,000		19,302,000							19,302,000		19,302,000		14,133,000		14,133,000										5,169,000		5,169,000
Transfers out of Level 3		(9,372,000)		(9,372,000)							(9,372,000)		(9,372,000)						(1,304,000)		(1,304,000)	(7,159,000)		(7,159,000)			(909,000)		(909,000)
Balance at end of period	24,985,000	31,174,000	24,985,000	31,174,000						23,610,000	28,663,000	23,610,000	28,663,000	15,090,000	14,122,000	15,090,000	14,122,000	85,000	90,000	85,000	90,000	279,000	2,000	279,000	2,000	8,433,000	14,172,000	8,433,000	14,172,000	1,375,000	2,511,000	1,375,000	2,511,000
Purchases, sales, or issues of investment securities							0		0
Interest in a limited partnership	600,000	600,000	600,000	600,000	600,000
Unrealized gains or losses recognized in earnings			0	0
Detail of purchases, sales, issues, and settlements of Level 3 assets and liabilities measured at fair value on a recurring basis
Purchases						2,016,000		2,016,000				2,016,000		2,016,000		2,016,000
Settlements						(75,000)		(5,736,000)				(5,725,000)				(481,000)							(149,000)			(75,000)		(5,095,000)				(11,000)
Total	$ 1,941,000	$ (781,000)	$ (3,720,000)	$ (5,382,000)		$ 1,941,000		$ (3,720,000)		$ 1,941,000	$ (781,000)	$ (3,709,000)	$ (4,446,000)	$ 2,016,000		$ 1,535,000	$ (2,987,000)		$ (62,000)		$ (179,000)	$ (456,000)	$ (149,000)	$ (808,000)		$ (75,000)	$ (263,000)	$ (5,095,000)	$ (472,000)			$ (11,000)	$ (936,000)