Repurchase Program (Details) - USD ($)	1 Months Ended	3 Months Ended	6 Months Ended
	Feb. 29, 2016	Mar. 31, 2016	Jun. 30, 2016	Jun. 30, 2015	Feb. 28, 2014	Apr. 30, 2013
Equity, Class of Treasury Stock [Line Items]
Purchase of senior notes			$ 9,206,000	$ 0
Stock repurchase program, remaining authorized repurchase amount			$ 33,500,000
Share repurchase program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount					$ 100,000,000.0	$ 50,000,000.0
Treasury stock, shares, acquired			0	0
Senior notes | Share repurchase program
Equity, Class of Treasury Stock [Line Items]
Debt instrument, repurchased face amount	$ 11,200,000	$ 11,200,000
Purchase of senior notes	$ 9,200,000	$ 9,200,000