Shareholders' Equity And Other Comprehensive Income (Summary Of Tax Effects Of Each Component Of Other Comprehensive Income) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Unrealized holding gains (losses) arising during the period, Before-Tax Amount	$ 3,195	$ 17,016	$ 2,139	$ 19,896
Other-than-temporary impairment realized in net income, Before-Tax Amount
Less: reclassification adjustment for (gains) included in net income, Before-Tax Amount	(901)	(1,426)	(3,702)	(1,427)
Net unrealized gains (losses), Before-Tax Amount	2,294	15,590	(1,563)	18,469
Change in fair value of derivative instruments designated as cash flow hedges during the period, Before-Tax Amount	(7,634)	(2,594)	(2,683)	(1,499)
Less: reclassification adjustment for losses (gains) included in net income, Before-Tax Amount	400	431	786	859
Fair value of derivative instruments designated as cash flow hedges, Before-Tax Amount	(7,234)	(2,163)	(1,897)	(640)
Total other comprehensive income, Before-Tax Amount	(4,940)	13,427	(3,460)	17,829
Unrealized holding gains (losses) arising during the period, Tax (Expense) Benefit	(1,118)	(5,955)	(749)	(6,964)
Other-than-temporary impairment realized in net income, Tax (Expense) Benefit
Less: reclassification adjustment for (gains) included in net income, Tax (Expense) Benefit	315	499	1,296	499
Net unrealized gains (losses), Tax (Expense) Benefit	(803)	(5,456)	547	(6,465)
Change in fair value of derivative instruments designated as cash flow hedges during the period, Tax (Expense) Benefit	2,672	908	939	525
Less: reclassification adjustment for losses (gains) included in net income, Tax (Expense) Benefit	(140)	(151)	(275)	(300)
Fair value of derivative instruments designated as cash flow hedges, Tax (Expense) Benefit	2,532	757	664	225
Total other comprehensive income, Tax (Expense) Benefit	1,729	(4,699)	1,211	(6,240)
Unrealized holding gains (losses) arising during the period, Net-of-Tax Amount	2,077	11,061	1,390	12,932
Other-than-temporary impairment realized in net income, Net-of-Tax Amount
Less: reclassification adjustment for (gains) included in net income, Net-of-Tax Amount	(586)	(927)	(2,406)	(928)
Net unrealized gains (losses), Net-of-Tax Amount	1,491	10,134	(1,016)	12,004
Change in fair value of derivative instruments designated as cash flow hedges during the period, Net-of-Tax Amount	(4,962)	(1,686)	(1,744)	(974)
Less: reclassification adjustment for losses (gains) included in net income, Net-of-Tax Amount	260	380	511	559
Fair value of derivative instruments designated as cash flow hedges, Net-of-Tax Amount	(4,702)	(1,406)	(1,233)	(415)
Other comprehensive income (loss), net of tax	$ (3,211)	$ 8,728	$ (2,249)	$ 11,589