Equity - Summary of activity under stock-based incentive plans (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Restricted Stock All [Member]
Summary of the activity under the incentive plans
Stock-based awards, beginning of period (shares)	1,855,325	1,813,073	1,788,168	1,770,061
Granted (shares)	26,677	20,256	128,199	87,043
Vested (shares)	(44,147)	(55,246)	(78,512)	(79,021)
Forfeited (shares)	0	0	0	0
Stock-based awards, end of period (shares)	1,837,855	1,778,083	1,837,855	1,778,083
Stock Incentive Plan [Member] | Restricted Stock [Member]
Summary of the activity under the incentive plans
Shares withheld to pay estimated withholding taxes			16,170	9,376