Earnings Per Share Antidilutive Securities Excluded from Earnings Per Share (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
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 EPS (in shares)			30,319
Weighted-average expense per share (in dollars per share)			$ 15.10
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 EPS (in shares)	25,113,350	32,216,245	30,862,794
Weighted-average conversion price (in dollars per share)	$ 19.55	$ 16.83	$ 13.81