Stock-Based Compensation (Summary of the Company's Restricted Stock Unit Activity) (Details)	9 Months Ended
	Sep. 30, 2015 shares
Restricted Stock Units
Restricted Stock Unit Activity, Outstanding [Roll Forward]
Outstanding at Beginning of Period	1,758,817
Granted	692,340
Vested	(688,811)
Forfeited	(93,746)
Outstanding at End of Period	1,668,600
Performance Shares
Restricted Stock Unit Activity, Outstanding [Roll Forward]
Outstanding at Beginning of Period	0	[1]
Granted	23,379	[1]
Vested	0	[1]
Forfeited	0	[1]
Outstanding at End of Period	23,379	[1]
2007 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
2007 Plan | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years

[1] Represents the target number of shares issuable at the end of the three-year performance cycle attributable to the first year’s performance period.