Stock-Based Compensation (RSU Activity) (Details)	3 Months Ended
	Mar. 31, 2016 USD ($) $ / shares shares
RSUs
Number of Shares
Balance at the beginning of the period (in shares) | shares	682,000
Granted (in shares) | shares	526,000
Vested (in shares) | shares	(266,000)
Cancelled (in shares) | shares	(17,000)
Balance at the end of the period (in shares) | shares	925,000
Weighted-Average Grant Date Fair Value
Balance at the beginning of the period (in dollars per share) | $ / shares	$ 30.18
Granted (in dollars per share) | $ / shares	27.55
Vested (in dollars per share) | $ / shares	30.31
Cancelled (in dollars per share) | $ / shares	30.18
Balance at the end of the period (in dollars per share) | $ / shares	$ 28.65
Restricted Stock | Performance-Based Vesting
Number of Shares
Balance at the beginning of the period (in shares) | shares	6,000
Vested (in shares) | shares	(6,000)
Weighted-Average Grant Date Fair Value
Balance at the beginning of the period (in dollars per share) | $ / shares	$ 27.21
Vested (in dollars per share) | $ / shares	$ 27.21
Restricted Stock | Outside directors
Number of Shares
Granted (in shares) | shares	1,420
Weighted-Average Grant Date Fair Value
Granted (in dollars per share) | $ / shares	$ 35.20
Additional Disclosure
Grant-date fair value (in dollars) | $	$ 50,000