Stock-Based Compensation (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock option / award activity
Options outstanding at the beginning of the period (in shares)	2,326,201	3,419,423	3,948,874
Granted (in shares)	0		756,000
Exercised (in shares)	(758,231)	(863,933)	(568,293)
Forfeited (in shares)	(182,473)	(229,289)	(717,158)
Options outstanding at the end of the period (in shares)	1,385,497	2,326,201	3,419,423	3,948,874
Available for future grant (in shares)	3,515,345	3,303,855	3,016,108
Total shares reserved at the end of period	4,900,842	5,630,056	6,435,531
Options exercisable at the end of period (in shares)	1,172,500	1,650,893	1,967,786
WEIGHTED-AVERAGE EXERCISE PRICE
Options outstanding at the beginning of the period (in dollars per option)	$ 27.02	$ 26.92	$ 28.91
Granted (in dollars per option)	$ 0.00		$ 18.55
Exercised (in dollars per option)	$ 27.18	$ 24.55	$ 18.89
Forfeited (in dollars per option)	$ 54.58	$ 34.88	$ 35.38
Options outstanding at the end of the period (in dollars per option)	$ 23.30	$ 27.02	$ 26.92	$ 28.91
Options exercisable at the end of period (in dollars per option)	$ 24.16	$ 30.74	$ 33.10
AVERAGE REMAINING CONTRACTUAL LIFE (in years)
Weighted average remaining contractual life, Options outstanding at the end of the period	2 years 2 months 12 days	2 years 3 months 18 days	2 years 10 months 24 days	2 years 4 months 24 days
Weighted average remaining contractual life, Options exercisable at the end of the period	1 year 10 months 24 days	1 year 7 months 6 days	1 year 7 months 6 days
AGGREGATE INTRINSIC VALUE
Aggregate intrinsic value, Options outstanding at the end of the period	$ 25,168,000	$ 44,123,000	$ 42,992,000
Aggregate intrinsic value, Options exercisable at the end of period	20,917,000	26,908,000	16,939,000
Stock options / awards
Stock-based compensation expense	18,600,000	19,500,000	17,800,000
Excess tax benefits	5,940,000	0	0
Intrinsic values of stock options exercised	11,200,000	15,300,000	5,400,000
Stock options
Stock-based compensation
Vesting period	3 years
Stock options / awards
Stock-based compensation expense	2,000,000	3,500,000	5,000,000
2011 Equity and Incentive Plan | Maximum
Stock-based compensation
Expiration period of stock options from date of grant	7 years
Predecessor plans to the 2011 Equity and Incentive Plan | Minimum
Stock-based compensation
Expiration period of stock options from date of grant	5 years
Predecessor plans to the 2011 Equity and Incentive Plan | Maximum
Stock-based compensation
Expiration period of stock options from date of grant	10 years
2004 Non-Employee Director Equity Plan and predecessor plans | Maximum
Stock-based compensation
Expiration period of stock options from date of grant	10 years
Non-Employee Director Stock Plans
Stock options / awards
Stock-based compensation expense	814,000	838,000	404,000
2011 Non-Employee Director Stock Plan (the Director Plan)
Stock-based compensation
Number of shares authorized for issuance to each director	3,000
The maximum period of time that can elapse subsequent to a new director's appointment prior to receipt of an initial award in accordance with the plan	30 days
Stock option / award activity
Available for future grant (in shares)	117,830	138,830
Restricted stock units
Stock-based compensation
Number of equal annual installments in which awards vest, with performance criteria	3
Stock options / awards
Stock-based compensation expense	$ 15,800,000	$ 15,100,000	$ 12,400,000
Restricted stock units | Senior executive officers
Stock-based compensation
Number of equal annual installments in which awards vest, with performance criteria	1