Long-Term Debt Long-Term Debt (Schedule Of Early Redemption)(Details) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Junior Subordinated Debt Redeemed, Par	$ 164,950	$ 3,093
Long-Term Subordinated Notes Redeemed, Par	0	84,444
Debt Redemptions and Repurchases, Par	265,418	287,695
Long-term Senior notes redeemed	100,468	27,281
FHLB Advances Redeemed, Par	500,000	22,009
Long-term Convertible Subordinated Notes Redeemed, Par	$ 0	150,868
Senior Notes, Coupon Rate Range Min [Member]
Debt Instrument [Line Items]
Senior Notes, rate	4.50%
Senior Notes, Coupon Rate Range Max [Member]
Debt Instrument [Line Items]
Senior Notes, rate	4.50%
Junior Subordinated Notes, Coupon Rate, 3mL 2.85% [Member]
Debt Instrument [Line Items]
Junior Subordinated Debt Redeemed, Par		3,093
Junior Subordinated Notes, Coupon Rate, 3mL 2.85% 3.38% [Member]
Debt Instrument [Line Items]
Junior Subordinated Debt Redeemed, Par	$ 51,547
Junior Subordinated Notes, Coupon Rate, 3mL 1.90% 2.22% [Member]
Debt Instrument [Line Items]
Junior Subordinated Debt Redeemed, Par	36,083
Junior Subordinated Notes, Coupon Rate, 3mL 1.78% 2.29% [Member]
Debt Instrument [Line Items]
Junior Subordinated Debt Redeemed, Par	61,856
Junior Subordinated Notes, Coupon Rate, 3mL 3.15% 3.75% [Member]
Debt Instrument [Line Items]
Junior Subordinated Debt Redeemed, Par	7,732
Junior Subordinated Notes, Coupon Rate, 3mL 2.89% 3.42% [Member]
Debt Instrument [Line Items]
Junior Subordinated Debt Redeemed, Par	7,732
Subordinated Note, Coupon Rate, 6.00% [Member]
Debt Instrument [Line Items]
Long-Term Subordinated Notes Redeemed, Par		32,366
Subordinated Note, Coupon Rate, 5.50% [Member]
Debt Instrument [Line Items]
Long-Term Subordinated Notes Redeemed, Par		52,078
Long-Term Debt, Senior Note at 3.30-3.70% [Member]
Debt Instrument [Line Items]
Long-term Senior notes redeemed		27,281
Long-Term Debt, Senior Note at 3.60% [Member]
Debt Instrument [Line Items]
Long-term Senior notes redeemed	11,108
Convertible Subordinated Notes, Coupon Rate, 6.00% [Member]
Debt Instrument [Line Items]
Long-term Convertible Subordinated Notes Redeemed, Par		79,276
Convertible Subordinated Notes, Coupon Rate, 5.50% [Member]
Debt Instrument [Line Items]
Long-term Convertible Subordinated Notes Redeemed, Par		$ 71,592
Long-Term Debt, Senior Note at 4.00% [Member]
Debt Instrument [Line Items]
Long-term Senior notes redeemed	$ 89,360