Consolidated Statements of Stockholders' Equity (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Consolidated Statements of Stockholders' Equity
Cash dividends declared on common stock, per share (in dollars per share)	$ 0.375	$ 0.625	$ 0.50
Common stock issued (in dollars per share)	$ 33.81	$ 33.71	$ 30.91