Shareholders' Equity and Common Stock Equivalents - Restricted Stock Activity (Details)	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Total Outstanding Units
Beginning balance, Total Outstanding, Units (in shares) | shares	1,149,679
Granted, Total Outstanding Units (in shares) | shares	188,675
Vested, Total Outstanding Units (in shares) | shares	0
Forfeited, Total Outstanding Units (in shares) | shares	(44,855)
Distributed, Total Outstanding Units (in shares) | shares	(285,250)
Ending balance, Total Outstanding, Units (in shares) | shares	1,008,249
Total Outstanding Units, Weighted Average Grant Date Fair Value per Unit
Beginning balance, Total Outstanding, Weighted Average Grant Date Fair Value per Unit (in usd per share) | $ / shares	$ 32.05
Granted, Total Outstanding, Weighted Average Grant Date Fair Value per Unit (in usd per share) | $ / shares	42.21
Vested, Total Outstanding, Weighted Average Grant Date Fair Value per Unit (in usd per share) | $ / shares	0
Forfeited, Total Outstanding, Weighted Average Grant Date Fair Value per Unit (in usd per share) | $ / shares	38.08
Distributed, Total Outstanding, Weighted Average Grant Date Fair Value per Unit (in usd per share) | $ / shares	25.15
Ending balance, Total Outstanding, Weighted Average Grant Date Fair Value per Unit (in usd per share) | $ / shares	$ 35.64
Vested Units
Beginning balance, Vested, Units (in shares) | shares	558,139
Granted, Vested, Units (in shares) | shares	0
Vested, Vested, Units (in shares) | shares	144,290
Forfeited, Vested, Units (in shares) | shares	0
Distributed, Vested, Units (in shares) | shares	(285,250)
Ending balance, Vested, Units (in shares) | shares	417,179
Vested Units, Weighted Average Grant Date Fair Value per Unit
Beginning balance, Vested, Weighted Average Grant Date Fair Value per Unit (in usd per share) | $ / shares	$ 19.80
Granted, Weighted Average Grant Date Fair Value per Unit (in usd per share) | $ / shares	0
Vested, Weighted Average Grant Date Fair Value per Unit (in usd per share) | $ / shares	31.58
Forfeited, Weighted Average Grant Date Fair Value per Unit (in usd per share) | $ / shares	0
Distributed, Vested, Weighted Average Grant Date Fair Value per Unit (in usd per share) | $ / shares	25.15
Ending balance, Vested, Weighted Average Grant Date Fair Value per Unit (in usd per share) | $ / shares	$ 20.22