Shareholders' Equity Shareholders' Equity (Details textual) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	0 Months Ended	3 Months Ended		3 Months Ended		1 Months Ended		3 Months Ended
	Mar. 09, 2013	Mar. 31, 2013	Feb. 06, 2013	Mar. 31, 2013 Common Stock and Additional Paid-in Capital	Mar. 31, 2013 Retained Earnings	Apr. 30, 2013 Accelerated share repurchase program [Member] Common Stock and Additional Paid-in Capital	Mar. 31, 2013 Accelerated share repurchase program [Member] Common Stock and Additional Paid-in Capital	Mar. 31, 2013 Accelerated share repurchase program [Member] Common Stock and Additional Paid-in Capital
Stockholders Equity Note [Line Items]
Common stock repurchased, shares				1.2		0.3	2.6
Stock Repurchased During Period, Value		$ 108,361,000						$ 75,000,000
Common stock authorized to be repurchased, number of shares (in shares)			25.0
Common stock dividends, paid per share (in dollars per share)	$ 0.09
Common stock dividends, total cash paid					$ 13,100,000