Summary of Significant Accounting Policies Antidilutive Securities Excluded from Earnings Per Share (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Number of stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0		0
Weighted-average shares of non-vested restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	0	56,175	0	56,175
Weighted-average expense per share (dollars per share)		$ 15.58		$ 15.58
Weighted-average number of shares issuable upon conversion of debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	32,493,002	28,310,522	29,105,625	28,310,522
Weighted-average conversion price (dollars per share)	$ 19.02	$ 15.22	$ 17.56	$ 15.22