Shareholders' Equity (Details) (USD $)	3 Months Ended						12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2012
Shareholders' Equity
Declared and paid a cash dividend on common stock							$ 0.12
Common stock dividends declared (in dollars per share)	$ 0.12	$ 0.12	$ 0.10	$ 0.10	$ 0.10	$ 0.10
Prior quarter dividend paid (in dollars per share)	$ 0.12
Current quarter dividend paid (in dollars per share)			$ 0.10	$ 0.10