Earnings Per Share Antidilutive Securities Excluded from Earnings Per Share (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Number of stock options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of EPS (in shares)	0	0	0
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of EPS (in shares)	0	28,875	3,859
Weighted-average expense per share (in dollars per share)		15.86	15.52
Weighted-average number of shares issuable upon conversion of debt [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of EPS (in shares)	30,682,138	29,393,137	19,854,510
Weighted-average conversion price (in dollars per share)	17.67	14.50	13.02