Stock-based Compensation - Summary of Restricted Stock Option (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Restricted shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted during the period (in shares)	0	28,000	855,000	54,000
SARs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted during the period (in shares)	100,000	104,000	185,000	703,000
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted during the period (in shares)	0	0	0	0