Shareholders' Equity and Earnings Per Share Shareholders' Equity And Earnings Per Share (Other Comprehensive Income Reclassified from AOCI) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2012	Dec. 31, 2011
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Accumulated other comprehensive (loss) income	$ (46,414)	$ 9,805	$ (46,414)	$ 9,805	$ (49,204)	$ 7,711	$ 1,971	$ (2,878)
Gains on available-for-sale securities, net	75	409	328	2,334
Interest on junior subordinated debentures	3,183	3,129	9,444	9,424
Income before taxes	58,082	52,173	166,618	131,261
Income tax expense	(22,519)	(19,871)	(64,696)	(50,154)
Net income	35,563	32,302	101,922	81,107
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	1,927	7,200	(56,716)	11,494
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(863)	(634)	(2,591)	(1,189)
Other Comprehensive Income (Loss), Net of Tax	2,790	7,834	(54,125)	12,683
Accumulated Unrealized Gains (Losses) on Securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Accumulated other comprehensive (loss) income	(42,718)	8,018	(42,718)	8,018	(41,213)	6,710	5,907	4,204
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(1,460)	2,358	(49,231)	5,214
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	45	247	197	1,400
Other Comprehensive Income (Loss), Net of Tax	(1,505)	2,111	(49,428)	3,814
Accumulated Unrealized Gains (Losses) on Securities | Reclassification Out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Gains on available-for-sale securities, net	75	409	328	2,334
Income before taxes	75	409	328	2,334
Income tax expense	(30)	(162)	(131)	(934)
Net income	45	247	197	1,400
Accumulated Unrealized Losses on Derivative Instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Accumulated other comprehensive (loss) income	(2,710)	(6,211)	(2,710)	(6,211)	(3,100)	(5,292)	(6,037)	(7,082)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(518)	(1,055)	(206)	(1,718)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(908)	(881)	(2,788)	(2,589)
Other Comprehensive Income (Loss), Net of Tax	390	(174)	2,582	871
Accumulated Unrealized Losses on Derivative Instruments | Reclassification Out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Interest on junior subordinated debentures	1,507	1,471	4,629	4,324
Income before taxes	(1,507)	(1,471)	(4,629)	(4,324)
Income tax expense	599	590	1,841	1,735
Net income	(908)	(881)	(2,788)	(2,589)
Accumulated Foreign Currency Translation Adjustment
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Accumulated other comprehensive (loss) income	(986)	7,998	(986)	7,998	(4,891)	6,293	2,101	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	3,905	5,897	(7,279)	7,998
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0	0	0
Other Comprehensive Income (Loss), Net of Tax	$ 3,905	$ 5,897	$ (7,279)	$ 7,998