Stockholders' Equity and Equity Compensation - Summary of Deferred Stock Unit Activity (Details)	6 Months Ended
	Jun. 30, 2018 $ / shares shares
Deferred Stock Units
Outstanding, beginning balance (in shares) | shares	1,428,878
Outstanding, ending balance (in shares) | shares	1,267,580
Weighted Average Award Date Fair Value
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 21.53
Outstanding, ending balance (in dollars per share) | $ / shares	$ 23.27
Deferred Stock Units
Deferred Stock Units
Outstanding, beginning balance (in shares) | shares	269,977
Awarded (in shares) | shares	41,855
Distributed (in shares) | shares	(20,939)
Outstanding, ending balance (in shares) | shares	290,893
Weighted Average Award Date Fair Value
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 20.14
Awarded (in dollars per share) | $ / shares	23.58
Distributed (in dollars per share) | $ / shares	19.48
Outstanding, ending balance (in dollars per share) | $ / shares	$ 20.68