Schedule II Condensed Financial Information of Registrant (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
ASSETS
Other assets	$ 228,264		$ 217,886
Total assets	8,826,672		8,167,726		7,435,169
LIABILITIES AND SHAREHOLDERS' EQUITY
Long-term debt	199,874		199,809
Other liabilities	366,013		445,952
Total liabilities	7,727,367		6,921,923
Preferred stock, $0.001 par value, authorized 1,000,000 shares; none issued	0		0
Common stock, $0.001 par value, authorized 75,000,000 shares; issued, 2013, 63,629,105; 2012, 62,311,787	64		62
Additional paid-in capital	407,056		383,135
Retained earnings	1,000,312		921,969
Accumulated other comprehensive income (loss), net of taxes:
Net unrealized gains on fixed maturities and equity securities	133,990	[1],[2]	382,400	[1],[2]
Net funded status of pension and other postretirement benefit obligations	(11,776)	[1]	(15,311)	[1]
Treasury stock, at cost, 2013, 23,117,554 shares; 2012, 22,943,925 shares	(430,341)		(426,452)
Total shareholders equity	1,099,305		1,245,803		1,055,353
Total liabilities and shareholders equity	8,826,672		8,167,726
Parent Company [Member]
ASSETS
Investments and cash	24,387		29,554
Investment in subsidiaries	1,282,614		1,406,641
Other assets	60,164		52,223
Total assets	1,367,165		1,488,418
LIABILITIES AND SHAREHOLDERS' EQUITY
Short-term debt	38,000		38,000
Long-term debt	199,874		199,809
Other liabilities	29,986		4,806
Total liabilities	267,860		242,615
Preferred stock, $0.001 par value, authorized 1,000,000 shares; none issued	0		0
Common stock, $0.001 par value, authorized 75,000,000 shares; issued, 2013, 63,629,105; 2012, 62,311,787	64		62
Additional paid-in capital	407,056		383,135
Retained earnings	1,000,312		921,969
Accumulated other comprehensive income (loss), net of taxes:
Net unrealized gains on fixed maturities and equity securities	133,990		382,400
Net funded status of pension and other postretirement benefit obligations	(11,776)		(15,311)
Treasury stock, at cost, 2013, 23,117,554 shares; 2012, 22,943,925 shares	(430,341)		(426,452)
Total shareholders equity	1,099,305		1,245,803
Total liabilities and shareholders equity	$ 1,367,165		$ 1,488,418

[1] All amounts are net of tax.

[2] The $22,245 pretax amount reclassified from accumulated other comprehensive income is included in net realized investment gains and losses and the $7,786 related tax expense (benefit) is included in income tax expense in the Consolidated Statement of Operations for the year ended December 31, 2013.