Stockholders' Equity - Narrative (Details) - USD ($)	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Class Of Stock [Line Items]
Stock repurchased and retired during period, shares	4,094,000	1,537,000
Original Repurchase [Member]
Class Of Stock [Line Items]
Stock repurchased program, authorized amount	$ 150,000,000
Combined Repurchase
Class Of Stock [Line Items]
Stock repurchased and retired during period, shares	3,920,920
Stock repurchased and retired during period, value	$ 181,100,000
New Repurchase [Member]
Class Of Stock [Line Items]
Stock repurchased program, authorized amount	200,000,000
Stock repurchase program, remaining authorized repurchase amount	$ 168,900,000
Restricted stock units (RSUs) [Member]
Class Of Stock [Line Items]
Share-based compensation arrangement by share-based payment award, non-option equity instruments, outstanding, number	1,200,000