Summary of Significant Accounting Policies - Share-based Compensation (Details) - Performance shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares awarded as a percentage of granted	130.00%	131.50%
Vesting period	3 years
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares awarded as a percentage of granted	50.00%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares awarded as a percentage of granted	150.00%