Stockholders' Equity - Narrative (Details) - $ / shares		3 Months Ended				12 Months Ended
	Feb. 12, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 02, 2017	May 01, 2017
Class of Stock [Line Items]
Dividend per share to common stockholders, paid (in dollars per share)		$ 0.3	$ 0.3	$ 0.3		$ 1.20	$ 1.20	$ 1.20
Dividends per share to common stockholders, declared (in dollars per share)					$ 0.30	$ 1.20
Common stock, authorized shares (shares)		300,000,000				300,000,000	300,000,000		300,000,000	150,000,000
Number of common shares authorized to be repurchased (shares)		3,000,000				3,000,000
Dividend Declared [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Dividends per share to common stockholders, declared (in dollars per share)	$ 0.30
Common Stock [Member]
Class of Stock [Line Items]
Issuance of common stock (shares)						26,203	8,395,607	14,063,100