Stock-Based Compensation - Performance Incentive Plan Vesting Levels (Details) - $ / shares	1 Months Ended	3 Months Ended
	Jul. 31, 2016	Dec. 31, 2017	Jan. 01, 2017
Performance stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance based compensation, peer group based		125.00%	120.00%
2008 Performance Incentive Plan | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Price Level	$ 50.00
Percentage of Total Award That Vests	100.00%
2008 Performance Incentive Plan | Restricted Stock Units (RSUs) | Performance Level One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Price Level	$ 50.00
Percentage of Total Award That Vests	25.00%
2008 Performance Incentive Plan | Restricted Stock Units (RSUs) | Performance Level Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Price Level	$ 60.00
Percentage of Total Award That Vests	50.00%
2008 Performance Incentive Plan | Restricted Stock Units (RSUs) | Performance Level Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Price Level	$ 70.00
Percentage of Total Award That Vests	25.00%