Stock-Based Compensation (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Stock option / award activity
Available for future grant (in shares)	3,132,053		3,132,053		3,016,108
Stock options / awards
Stock-based compensation expense	$ 4,500,000	$ 4,500,000	$ 13,700,000	$ 11,700,000
Stock options
Stock-based compensation
Vesting period			3 years
Stock option / award activity
Options outstanding at the beginning of the period (in shares)			3,419,423	3,948,874	3,948,874
Granted (in shares)			0	756,000
Exercised (in shares)			(815,394)	(380,813)
Forfeited (in shares)			(60,289)	(699,498)
Options outstanding at the end of the period (in shares)	2,543,740	3,624,563	2,543,740	3,624,563	3,419,423	3,948,874
Available for future grant (in shares)	3,132,053	3,071,288	3,132,053	3,071,288
Total shares reserved at the end of period	5,675,793	6,695,851	5,675,793	6,695,851
Options exercisable at the end of period (in shares)	1,839,432	2,172,926	1,839,432	2,172,926
WEIGHTED-AVERAGE EXERCISE PRICE
Options outstanding at the beginning of the period (in dollars per option)			$ 26.92	$ 28.91	$ 28.91
Granted (in dollars per option)			$ 0.00	$ 18.55
Exercised (in dollars per option)			$ 25.07	$ 18.30
Forfeited (in dollars per option)			$ 21.24	$ 35.33
Options outstanding at the end of the period (in dollars per option)	$ 27.65	$ 26.62	$ 27.65	$ 26.62	$ 26.92	$ 28.91
Options exercisable at the end of period (in dollars per option)	$ 31.38	$ 32.01	$ 31.38	$ 32.01
WEIGHTED-AVERAGE REMAINING CONTRACTUAL LIFE (in years)
Weighted average remaining contractual life, Options outstanding at the end of the period			2 years 6 months	3 years	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 8 months 12 days	1 year 9 months 18 days
AGGREGATE INTRINSIC VALUE
Aggregate intrinsic value, Options outstanding at the end of the period	40,113,000	28,297,000	40,113,000	28,297,000
Aggregate intrinsic value, Options exercisable at the end of period	24,172,000	11,667,000	24,172,000	11,667,000
Stock options / awards
Stock-based compensation expense	699,000	1,400,000	2,800,000	3,700,000
Intrinsic values of stock options exercised	756,000	2,400,000	14,100,000	2,700,000
2011 Equity and Incentive Plan
Stock-based compensation
Number of equal annual installments in which awards vest, with performance criteria			3
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	205,000	108,000	589,000	296,000
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)	140,000		140,000		158,000
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	$ 3,600,000	$ 2,900,000	$ 10,300,000	$ 7,700,000