Cash Dividends (Tables)

6 Months Ended

Jun. 30, 2013

Stockholders' Equity Note [Abstract]

Schedule of Conversion Rates for Convertible Notes

Convertible Notes	Conversion Rate per $1,000 Principal Amount	Approximate Conversion Price Per Common Share		Effective Date
Series 2012 Notes	176.389	$	5.67	June 3, 2013
May 2015 Notes	154.4189	$	6.48	June 3, 2013
February 2015 Notes	176.389	$	5.67	June 6, 2013