Stock Based Compensation (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average fair value per share (in dollars per share)	$ 9.31	$ 7.21
Total compensation cost related to unvested share-based awards not yet recognized	$ 6,298
Weighted average vesting period	2 years 7 months 6 days
Number of Shares [Roll Forward]
Outstanding, beginning balance (in shares)	2,070,672
Granted (in shares)	29,500
Exercised (in shares)	(212,276)
Forfeited or expired (in shares)	(80,375)
Outstanding, ending balance (in shares)	1,807,521
Options exercisable (in shares)	787,021
Weighted Average Exercise Price [Roll Forward]
Outstanding, beginning balance (in dollars per share)	$ 12.08
Granted (in dollars per share)	$ 23.45
Exercised (in dollars per share)	$ 7.25
Forfeited or expired (in dollars per share)	$ 14.48
Outstanding, ending balance (in dollars per share)	$ 12.72
Exercisable, ending balance (in dollars per share)	$ 9.08
Aggregate intrinsic value exercised	5,340	1,641
Aggregate intrinsic value outstanding	48,639
Aggregate intrinsic value exercisable	24,043
Stock Options [Member] | Selling, General and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option expense	605	554
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period	3 years
Performance Shares [Member] | Selling, General and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share expense	472	360
Cash Settled Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance period	3 years
Cash Settled Performance Share Units [Member] | Selling, General and Administrative Expenses [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance share unit expense	$ 0	$ 193
Nonvested Stock Option [Member]
Nonvested Stock Options, Number of Shares [Roll Forward]
Nonvested, beginning balance (in shares)	1,098,875
Granted (in shares)	29,500
Vested during period (in shares)	(27,500)
Forfeited (in shares)	(80,375)
Nonvested, ending balance (in shares)	1,020,500
Nonvested Stock Options, Weighted-Average Grant-Date Fair Value [Roll Forward]
Nonvested, beginning balance (in dollars per share)	$ 7.14
Granted (in dollars per share)	$ 9.31
Vested during period (in dollars per share)	$ 4.02
Forfeited (in dollars per share)	$ 6.90
Nonvested, ending balance (in dollars per share)	$ 7.30