Stockholders' Equity - Stock Appreciation Rights (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Grants in Period, Weighted Average Exercise Price (in usd per share)		$ 0	$ 0.00
Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Maximum contractual term of SARs with final vesting date of December 31, 2011 (in years)		10 years
Maximum contractual term of SARs with final vesting date of December 31, 2016 (in years)		15 years
Stock Appreciation Rights (SARs) | Equity Incentive Plans 2006
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Nonvested at the beginning of the period (in shares)	730	715	730	745
Outstanding at the beginning of the period (in dollars per share)	$ 26.73	$ 26.73	$ 26.73	$ 26.73
Outstanding at the beginning of the period (in years)	6 years 8 months 12 days	3 years 6 months	5 years 9 months 18 days	6 years 11 months 12 days	7 years 10 months 17 days
Outstanding at the beginning of the period (in dollars)	$ 38,700	$ 20,600	$ 33,000	$ 42,100	$ 10,100
Granted (in shares)	0	0	0	0
Grants in Period, Weighted Average Exercise Price (in usd per share)	$ 0.00			$ 0.00
Exercised (in shares)	0	(80)	(15)	(15)
Exercised (in dollars per share)	$ 0.00	$ 26.73	$ 26.73	$ 26.73
Forfeited (in shares)	0	(15)	0	0
Forfeited (in dollars per share)	$ 0.00	$ 26.73	$ 0.00	$ 0.00
Nonvested at the end of the period (in shares)	730	620	715	730	745
Outstanding at the end of the period (in dollars per share)	$ 26.73	$ 26.73	$ 26.73	$ 26.73	$ 26.73
Outstanding at the end of the period (in years)	6 years 8 months 12 days	3 years 6 months	5 years 9 months 18 days	6 years 11 months 12 days	7 years 10 months 17 days
Outstanding at the end of the period (in dollars)	$ 38,700	$ 20,600	$ 33,000	$ 42,100	$ 10,100
Exercisable at the end of the period (in shares)		530
Exercisable at the end of the period (in dollars per share)		$ 26.73
Exercisable at the end of the period (in years)		3 years 3 months 18 days
Exercisable at the end of the period (in dollars)		$ 17,600
Expected to vest and exercisable (in shares)		620
Expected to vest and exercisable (in dollars per share)		$ 26.73
Expected to vest and exercisable (in years)		3 years 6 months
Expected to vest and exercisable (in dollars)		$ 20,600