Schedule II - Condensed Financial Information Of Registrant (Notes To Condensed Financial Statements) (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Condensed Financial Statements, Captions [Line Items]
Dividends from subsidiaries	$ 437,000,000
Stock-based compensation not involving cash	21,605,000	[1]	14,954,000	[1]	11,848,000	[1]
Debt assumed to acquire Family Heritage	20,000,000		0		0
Interest paid	77,686,000		75,653,000		76,911,000
Preferred stock, shares outstanding	0		0
Parent Company
Condensed Financial Statements, Captions [Line Items]
Dividends from subsidiaries	436,814,000		769,139,000		370,947,000
Stock-based compensation not involving cash	21,605,000		14,954,000		11,848,000
Debt assumed to acquire Family Heritage	20,000,000		0		0
Interest paid	76,833,000		74,569,000		75,909,000
Income taxes received	29,251,000		22,893,000		2,379,000
Preferred stock, liquidation distribution available to stockholders, per share in thousands	$ 1,000
Preferred stock, liquidating distribution legally available, aggregate value	$ 351,000,000
Cumulative Series A Preferred Stock | Parent Company
Condensed Financial Statements, Captions [Line Items]
Preferred stock, shares issued	351,000
Preferred stock, shares outstanding	351,000
6.50% Cumulative Preferred Stock, Series A | Parent Company
Condensed Financial Statements, Captions [Line Items]
Preferred stock, shares issued	280,000
Preferred stock, shares outstanding	280,000
Preferred stock, dividend rate, percentage	6.50%
7.15% Cumulative Preferred Stock, Series A | Parent Company
Condensed Financial Statements, Captions [Line Items]
Preferred stock, shares issued	71,000
Preferred stock, shares outstanding	71,000
Preferred stock, dividend rate, percentage	7.15%

[1] No stock-based compensation expense was capitalized in any period.