Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Statement of Stockholders' Equity [Abstract]
Unrealized loss on investment, tax	$ 0	$ 59	$ 30
Reclassification adjustment for gain realized on investment, tax	$ 0	$ 0	$ 7,494
Dividends paid, per share	$ 0.71	$ 0.69	$ 0.68