Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Thousands	Total		Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Common Class A [Member]	Common Class A [Member] Common Stock [Member]	Common Class A [Member] Retained Earnings [Member]	Common Class B [Member]	Common Class B [Member] Common Stock [Member]	Common Class B [Member] Surplus [Member]	Common Class B [Member] Retained Earnings [Member]	Common Class B [Member] Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2009	$ 1,559,115		$ 143,766	$ 1,429,863	$ (24,949)	$ 8,757			$ 1,678
Comprehensive income:
Net income	162,959		0	162,959	0	0			0
Change in unrealized securities gains arising during period, net of deferred tax	5,567		0	0	5,567	0			0
Reclassification adjustment for (gains)/losses included in net income, net of deferred tax (benefit)	(1,398)		0	0	(1,398)	0			0
Change in pension liability, net of deferred tax	1,830		0	0	1,830	0			0
Change in unrecognized loss on cash flow hedges, net of deferred tax benefit	(5,383)		0	0	(5,383)	0			0
Total comprehensive income	163,575
Cash dividends	(9,390)		0	(9,390)	0	0			0
Balance at Sep. 30, 2010	1,718,204	[1]	143,766	1,588,336	(24,333)	8,757			1,678
Balance at Dec. 31, 2010	1,732,962	[2]	143,766	1,615,290	(36,529)	8,757			1,678
Comprehensive income:
Net income	164,995		0	164,995	0	0			0
Change in unrealized securities gains arising during period, net of deferred tax	3,240		0	0	3,240	0			0
Reclassification adjustment for (gains)/losses included in net income, net of deferred tax (benefit)	198		0	0	198	0			0
Change in pension liability, net of deferred tax	3,008		0	0	3,008	0			0
Change in unrecognized loss on cash flow hedges, net of deferred tax benefit	(2,444)		0	0	(2,444)	0			0
Total comprehensive income	168,997
Repurchase of shares of common stock						(13,063)	(88)	(12,975)	(7,602)	(38)	0	(7,564)	0
Cash dividends	(9,364)		0	(9,364)	0	0			0
Balance at Sep. 30, 2011	$ 1,871,930	[1]	$ 143,766	$ 1,750,382	$ (32,527)	$ 8,669			$ 1,640

[1] Unaudited

[2] Derived from 2010 Annual Report on Form 10-K.