Earnings Per Share & Pro Forma Earnings Per Share - Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
Basic:
Net income attributable to common stock, basic					$ 54,587
Net income attributable to common stock, basic (in shares)					42,015
Net income attributable to common stock, basic, (in dollars per share)	$ 0.43	$ 0.33	$ 0.37	$ 0.15	$ 1.30
Effect of Dilutive Securities:
Dilutive effect of potential common shares issuable					0	0
Dilutive effect of potential common shares issuable (in shares)					240	3
Diluted:
Net income attributable to common stock, diluted					$ 54,587
Net income attributable to common stock, diluted (in shares)					42,255
Net income attributable to common stock, diluted (in dollars per share)	$ 0.42	$ 0.33	$ 0.36	$ 0.15	$ 1.29