Consolidated Statement of Stockholders' Equity (Unaudited) (USD $) In Thousands, unless otherwise specified		Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]
Balance at Dec. 31, 2011		$ 696,141	$ 25	$ 213,045	$ 400,485	$ 82,586
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		19,184			19,184
Summary of changes
Compensation expense and related tax benefit for stock based award grants				405
Stock repurchased			0	0
Shares issued for stock-based awards (97,000 shares)			1	42
Dividends on common stock ($0.15 per share)					(3,826)
Change in net unrealized appreciation	[1]					7,025
Change in underfunded status of employee benefit plans	[2]					418
All other changes in stockholders' equity accounts		4,065
Balance at Mar. 31, 2012		$ 719,390	$ 26	$ 213,492	$ 415,843	$ 90,029

[1] The change in net unrealized appreciation is net of reclassification adjustments and income taxes.

[2] The recognition of the underfunded status of employee benefit plans is net of income taxes.