Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Net income attributable to common shareholders	$ 23,312	$ 4,453
Weighted average common shares outstanding - basic (in shares)	111,728	111,296
Net effect of dilutive securities:
Contingently issuable performance shares and restricted stock units (in shares)	467	551
Weighted average common shares outstanding — diluted (in shares)	112,195	111,847
Earnings per weighted-average common share outstanding
Net income attributable to common shareholders - basic (in dollars per share)	$ 0.21	$ 0.04
Net income attributable to common shareholders - diluted (in dollars per share)	$ 0.21	$ 0.04