Stockholders' Equity - Common and Preferred Stock (Details)													3 Months Ended	12 Months Ended
	Feb. 20, 2019 USD ($) shares	Jan. 02, 2019 USD ($)	Nov. 13, 2018 USD ($) shares	Oct. 01, 2018 USD ($)	Jul. 02, 2018 USD ($)	Apr. 02, 2018 USD ($)	Jan. 02, 2018 USD ($)	Oct. 02, 2017 USD ($)	Jul. 03, 2017 USD ($)	Apr. 03, 2017 USD ($)	Feb. 17, 2016 USD ($) shares	Jan. 04, 2016 USD ($) shares	Feb. 20, 2019 USD ($) shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) vote_per_stock $ / shares shares	Dec. 31, 2016 USD ($)	Nov. 06, 2018 USD ($)	Sep. 30, 2018 $ / shares shares	Jun. 30, 2018 $ / shares shares	Mar. 31, 2018 $ / shares shares	Mar. 15, 2018 shares	Nov. 01, 2016 shares
Class of Stock [Line Items]
Capital stock, shares authorized (in shares) | shares																						155,000,000
Common stock, shares authorized (in shares) | shares														150,000,000	150,000,000			150,000,000	150,000,000	150,000,000		150,000,000
Preferred stock, shares authorized (in shares) | shares																						5,000,000
Proceeds from issuance of common stock											$ 286,000,000.0			$ 0	$ 0	$ 286,003,000
Preferred stock, shares issued (shares) | shares																					200,000
Series F Preferred Stock issuance														$ 11,880,000	$ 0	$ 0
Series F
Class of Stock [Line Items]
Preferred stock, per share liquidation value (usd per share) | $ / shares														$ 20
Preferred stock, shares outstanding (in shares) | shares														0
Preferred stock, shares issued (shares) | shares														0
Series B
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares) | shares														5,000,000	5,000,000			5,000,000	5,000,000	5,000,000
Voting rights per stock (vote per stock) | vote_per_stock															0.054
Shares convertible for each stock (in shares) | shares															0.054
Preferred stock, per share liquidation value (usd per share) | $ / shares														$ 29	$ 29			$ 29	$ 29	$ 29
Dividends declared per share (usd per share) | $ / shares															$ 2.90
Preferred stock, shares outstanding (in shares) | shares														44,258	44,258			44,258	44,258	44,258
Dividends, Preferred Stock, Cash				$ 32,087	$ 32,087	$ 32,087	$ 32,087	$ 32,087	$ 32,087	$ 32,087
Preferred stock, shares issued (shares) | shares														44,258	44,258			44,258	44,258	44,258
Common Stock
Class of Stock [Line Items]
Price per share on issuable shares (usd per share) | $ / shares															$ 3.77
Number of trading dates used to calculated price per share															20 days
Transferable Subscription Rights [Member]
Class of Stock [Line Items]
Common stock, shares authorized (in shares) | shares												20,138,888
Proceeds from Issuance of Private Placement											$ 290,000,000
Value of subscription rights to be exercised within 10 days of commencement												$ 30,000,000
Value of subscription rights to be exercised, maximum												290,000,000
Sale of stock, commitment fee												$ 1,500,000
Sale of stock, commitment fee, percent												0.50%
Common Stock | Transferable Subscription Rights [Member]
Class of Stock [Line Items]
Shares, Issued | shares											20,138,888
Common Stock | Basic Subscription Rights [Member] | Transferable Subscription Rights [Member]
Class of Stock [Line Items]
Shares, Issued | shares											176,086
Common Stock | Over Subscription Rights [Member] | Transferable Subscription Rights [Member]
Class of Stock [Line Items]
Shares, Issued | shares											13,136,817
Kien Huat Realty Limited [Member] | Common Stock | Standby Purchase Agreement [Member]
Class of Stock [Line Items]
Shares, Issued | shares											6,825,985
Kien Huat Realty III Limited [Member] | 2018 Kien Huat Preferred Stock Commitment Letter [Member]
Class of Stock [Line Items]
Related Party Transaction, Equity Financing, Maximum Without Reduction to Commitment Amount																	$ 29,000,000
Funding Fee, Percent																	1.00%
Kien Huat Realty III Limited [Member] | 2018 Kien Huat Preferred Stock Commitment Letter [Member] | Series F
Class of Stock [Line Items]
Share Purchase Agreement, Maximum Purchase Amount																	$ 126,000,000
Share Purchase Agreement, Recorded Commitment																	31,100,000
Kien Huat Realty Limited [Member] | Expense Reimbursement [Member]
Class of Stock [Line Items]
Related Party Transaction, Amounts of Transaction											$ 50,000
Kien Huat Realty Limited [Member] | 2018 Kien Huat Preferred Stock Commitment Letter [Member] | Series F
Class of Stock [Line Items]
Preferred stock, shares issued (shares) | shares			120
Proceeds from Issuance of Preferred Stock and Preference Stock, Gross			$ 12,000,000
Issuance of Preferred Stock and Preference Stock, Funding Fee			120,000
Series F Preferred Stock issuance			$ 11,900,000
Subsequent Event | Series B
Class of Stock [Line Items]
Dividends, Preferred Stock, Cash		$ 32,087
Subsequent Event | Kien Huat Realty III Limited [Member] | 2018 Kien Huat Preferred Stock Commitment Letter [Member] | Series F
Class of Stock [Line Items]
Preferred stock, shares issued (shares) | shares	320												320
Proceeds from Issuance of Preferred Stock and Preference Stock, Gross													$ 32,000,000
Series F Preferred Stock issuance													31,700,000
Subsequent Event | Kien Huat Realty Limited [Member] | 2018 Kien Huat Preferred Stock Commitment Letter [Member]
Class of Stock [Line Items]
Issuance of Preferred Stock and Preference Stock, Funding Fee	$ 300,000												$ 300,000
Subsequent Event | Kien Huat Realty Limited [Member] | 2018 Kien Huat Preferred Stock Commitment Letter [Member] | Series F
Class of Stock [Line Items]
Preferred stock, shares issued (shares) | shares	200												200
Proceeds from Issuance of Preferred Stock and Preference Stock, Gross	$ 20,000,000
Issuance of Preferred Stock and Preference Stock, Funding Fee	200,000												$ 200,000
Series F Preferred Stock issuance	$ 19,800,000
Share Purchase Program Schedule, Period One [Member] | Kien Huat Realty III Limited [Member] | 2018 Kien Huat Preferred Stock Commitment Letter [Member] | Series F
Class of Stock [Line Items]
Share Purchase Agreement, Maximum Purchase Amount																	12,000,000
Share Purchase Program Schedule, Period Two [Member] | Kien Huat Realty III Limited [Member] | 2018 Kien Huat Preferred Stock Commitment Letter [Member] | Series F
Class of Stock [Line Items]
Share Purchase Agreement, Maximum Purchase Amount																	20,000,000
Share Purchase Program Schedule, Period Three [Member] | Kien Huat Realty III Limited [Member] | 2018 Kien Huat Preferred Stock Commitment Letter [Member] | Series F
Class of Stock [Line Items]
Share Purchase Agreement, Maximum Purchase Amount																	20,000,000
Share Purchase Program Schedule, Period Four [Member] | Kien Huat Realty III Limited [Member] | 2018 Kien Huat Preferred Stock Commitment Letter [Member] | Series F
Class of Stock [Line Items]
Share Purchase Agreement, Maximum Purchase Amount																	15,000,000
Share Purchase Program Schedule, Period Five [Member] | Kien Huat Realty III Limited [Member] | 2018 Kien Huat Preferred Stock Commitment Letter [Member] | Series F
Class of Stock [Line Items]
Share Purchase Agreement, Maximum Purchase Amount																	37,000,000
Share Purchase Program Schedule, Period Six [Member] | Kien Huat Realty III Limited [Member] | 2018 Kien Huat Preferred Stock Commitment Letter [Member] | Series F
Class of Stock [Line Items]
Share Purchase Agreement, Maximum Purchase Amount																	$ 22,000,000