Shareholder-Designated Contribution Plan (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Shareholder-Designated Contribution Plan [Abstract]
Shareholder-designated contribution	$ 0	$ 0	$ 5,000,000	$ 0
Shareholder-designated contribution, diluted per share (in dollars per share)			$ 0.11
Initial contribution per registered share to Shareholder-designated charitable contribution program (in dollars per share)			$ 0.25
Expected expense related to Shareholder-designated charitable contribution program			$ 5,300,000