Basis of Condensed Consolidated Financial Statements - (Narrative) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Reduction in net increase in deposits with banks			$ (2,888)	$ (512)
Cash and cash equivalents—Beginning of period			834,837	670,529
Cash and cash equivalents—End of period	1,203,873	867,279	1,203,873	867,279
Income taxes receivable					37,632
Deferred income tax assets	27,478		27,478		27,478
Deferred income taxe liability	97,174		97,174		93,362
Other operating expenses	219,536	222,297	622,024	660,408
Restatement Adjustment | Compensating Errors
Reduction in net increase in deposits with banks				(9,900)
Cash and cash equivalents—Beginning of period				43,300
Cash and cash equivalents—End of period		33,400		33,400
Income taxes receivable					11,100
Deferred income tax assets					27,500
Deferred income taxe liability					38,600
Other operating expenses			$ 4,300