Weighted Average Shares Outstanding (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jun. 30, 2014	Jun. 24, 2014	Jun. 16, 2014
Weighted Average Shares Outstanding [Line Items]
Basic (in shares)	55,028,063	54,791,030	53,860,308
Dilutive effect of:
Diluted (in shares)	55,513,219	55,723,267	54,973,344
Incremental Common Shares Attributable to Conversion of Debt Securities	0	245,230	209,321
3.375% Convertible Notes [Member] | Convertible Debt [Member]
Dilutive effect of:
Convertible Note Repurchases, Par Value						$ 224
Convertible notes stated interest rate				3.375%		3.375%
Convertible notes					$ 55,412
Stock options [Member]
Dilutive effect of:
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	214,032	89,924	133,162
Stock options [Member]
Dilutive effect of:
Shares attributable to share-based payment arrangements (in shares)	206,778	355,595	575,202
Performance share awards [Member]
Dilutive effect of:
Shares attributable to share-based payment arrangements (in shares)	278,378	319,704	280,488
Non Employee Director Deferred Stock Plan [Member]
Dilutive effect of:
Shares attributable to share-based payment arrangements (in shares)	0	11,708	48,025